Steve Sinner at advancedlathetools.com makes nice double boring bars and a very robust and good "trap". Has anyone made a double boring bar system like his. I'm thinking of making one out of 1 1/8th cold formed rod that are tig welded and drilled at the end to receive a cutter holder.
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Double Boring Bar- has anyone made one
- Thread starter Brian Rohde
- Start date
I've made articulated hollowing systems and larger diameter bars for my Jamieson hollowing tools. If you make your entire system out of 1 1/8" bar, It's going to be super heavy for doing small and medium sized vessels. That is why I made heavy bars for the Jamieson tool. The overhang over the tool rest into the vessel is what has to be stiff. The bars in the trap have little bending load on it.
Thank you for your sharing your experience. The advanced lathe tool trap is adjustable to use 3/4" to 1 1/4" boring bars. The first ones I want to make will be 1 1/8th" welded together. There will be a short tool holder in the end of the 1 1/8th bar that will overhang the tool rest. If this works for the larger vessels I'll make a smaller boring bar out of 3/4". Do you use your articulated system for you small hollowing?
Okay, since I don't do much hollowing, what is a double boring bar? I am familiar with the D type set ups, like many use and sell.
robo hippy
robo hippy
The standard Jamieson hollower has two bars, but they are spread wide and prevent the torquing of the system. Steve Sinner just welds two bars side by side (double bars) to resist the torquing. Both work the same way by being captured inside 2 parallel spaced bars mounted on the back of the lathe or through a floor stand. Sinner uses much larger diameter bars.
I built a copy oj the Jamieson system. Several years ago I shortened the outrigger by half the width. Being captured and everything set up on center the twisting torque really isnt there. I plan to make it a double bar sometime like the Sinber system. Takes a lot less room to store
I guess i built one similar but i used 2 pieces of 1 inch square tubing welded together along with some off the shelf plumbing parts to attach my boring bars and camera. I did turn an aluminum insert to hold the bars in.
If you have Lyle’s bent swivel holder and mount it in the angled mount, it does generate significant torque due to being offset several inches from center. I do believe a narrower D handle, or 2 bars welded will work though.
I hang the handle and laser support assm from the ceiling to store, so no benefit to going narrower there, but it will give more side swing w/o having to move the backrest over.
Steve Sinner's advancedlathetools.coms shows the double boring bar. For the 1 1/8th in setup which will go 24" beyond the toolrest he has welded a 58" bar to a 46" bar with the 12" single bar the working end. The two bars are placed horizontally in his adjustable trap to resist the torque.
I made one. It works well. I use it with the Pro Hogger from AZ CARBIDE. I am trying to use it through a smaller opening.
For deeper hollowing than can be done with the single bar extension you will have to use a bigger opening for the two bars side by side than you could with a single round bar large enough to take the stress. The advantage of the doubled bar seems to be more maneuverability in the rear trap than a d shape so there's the tradeoff.
Easier to make as well.
I used and will illustrate something similar to The Steve Sinner double welded 1.25" boring bars. I have posted in the past about my boring bar journey. Please read this previous post as there may be some useful info for you.
www.aawforum.org
The advantage of the Sinner bar is that two bars are much stronger than 1 bar and for the same length you have increased your hollowing depth capabilities. A bonus is the double bar acts as a torque arrestor while being held in Sinner's dual bar trap. I borrowed this idea in my own home grown custom boring bar system. If you view the last photo in the post above or the first one below in this post, you will see that the 1.5" boring bars from Clark system are connected to a Jamison-like d-bar trap. (There is a 3/4" interface on all Clarks bars allowing me to connect it to the bar. Sinner's tool interface is 5/8). My D bar's sole purpose was to add stability but it was hitting the back wall from the lathe with deeper turnings and taking away from using a longer Clark 1.5" bars. (see last photo in the link above). To solve this I used Sinner's Idea but I didn't weld two bars directly together. I had a few pairs of 1.5-inch motor shaft collars welded together and I connect the bars with their set screws. Here are some photos illustrating this. I have enhanced the trap by reinforcing it with a straight bar, bigger screws, and beefer springs in the second photo below.
,
This photo shows my how my laser assembly is attached to the boring bar.
Hope this gives you some alternatives.
Hollowing system boring bars
I have the Hope hollowing system. I have the 3/4" bars straight and bent that are great. I can use carbide or HSS scrapers. I also have the Hope 5/8" bar that only uses the carbide cutters. These cutters seem very aggressive, most likely caused by my inexperience. The carbide cutters are...
The advantage of the Sinner bar is that two bars are much stronger than 1 bar and for the same length you have increased your hollowing depth capabilities. A bonus is the double bar acts as a torque arrestor while being held in Sinner's dual bar trap. I borrowed this idea in my own home grown custom boring bar system. If you view the last photo in the post above or the first one below in this post, you will see that the 1.5" boring bars from Clark system are connected to a Jamison-like d-bar trap. (There is a 3/4" interface on all Clarks bars allowing me to connect it to the bar. Sinner's tool interface is 5/8). My D bar's sole purpose was to add stability but it was hitting the back wall from the lathe with deeper turnings and taking away from using a longer Clark 1.5" bars. (see last photo in the link above). To solve this I used Sinner's Idea but I didn't weld two bars directly together. I had a few pairs of 1.5-inch motor shaft collars welded together and I connect the bars with their set screws. Here are some photos illustrating this. I have enhanced the trap by reinforcing it with a straight bar, bigger screws, and beefer springs in the second photo below.
,
This photo shows my how my laser assembly is attached to the boring bar.
Hope this gives you some alternatives.
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I have built many boring bars I still have a couple like the Jamieson , built a Kobra type with multi link and a sliding bar for various depths, sold it off preferring fewer complications and have a couple of captured bars. But these days I tend hollow with a single bar made from a pneumatic cylinder rod High tensile, often hard chromed and very stiff 20-25mm in dia. Just tuck it under the arm pit and away I go.
The only bars I use are the 3/4" and 1" bars from Mike Hunter used with his 3 tool cutter package. With the 3/4" bar and cutters I easily go 12" with no vibration and I can get 18 or 19 inches deep with no vibration using the 1" bar and 3 tool set. I can use them with any of my three hollowing systems with the same results.
Some very nice machining for sure. Thanks for the pics and the explanation. I like the square tubing trap. What is the length, the size of the tubing and the distance to the post. I assume the added piece underneath is to reduce friction on the tubing surface...is that what it for and what is it made of? It seems simpler to weld the bars together than to use the collars. Am I missing something about the advantage to the collars?I used and will illustrate something similar to The Steve Sinner double welded 1.25" boring bars. I have posted in the past about my boring bar journey. Please read this previous post as there may be some useful info for you.
Hollowing system boring bars
I have the Hope hollowing system. I have the 3/4" bars straight and bent that are great. I can use carbide or HSS scrapers. I also have the Hope 5/8" bar that only uses the carbide cutters. These cutters seem very aggressive, most likely caused by my inexperience. The carbide cutters are...
The advantage of the Sinner bar is that two bars are much stronger than 1 bar and for the same length you have increased your hollowing depth capabilities. A bonus is the double bar acts as a torque arrestor while being held in Sinner's dual bar trap. I borrowed this idea in my own home grown custom boring bar system. If you view the last photo in the post above or the first one below in this post, you will see that the 1.5" boring bars from Clark system are connected to a Jamison-like d-bar trap. (There is a 3/4" interface on all Clarks bars allowing me to connect it to the bar. Sinner's tool interface is 5/8). My D bar's sole purpose was to add stability but it was hitting the back wall from the lathe with deeper turnings and taking away from using a longer Clark 1.5" bars. (see last photo in the link above). To solve this I used Sinner's Idea but I didn't weld two bars directly together. I had a few pairs of 1.5-inch motor shaft collars welded together and I connect the bars with their set screws. Here are some photos illustrating this. I have enhanced the trap by reinforcing it with a straight bar, bigger screws, and beefer springs in the second photo below.
,View attachment 49764
View attachment 49770
This photo shows my how my laser assembly is attached to the boring bar.
View attachment 49771
Hope this gives you some alternatives.
I'm seeing some very interesting ideas and different approaches. Thanks to everyone for their contribution to this discussion.
@Brian Rohde : I like the square tubing trap. What is the length, the size of the tubing and the distance to the post. This was an original that I bought in 2002 that is no longer available. It was good to use withe the 3/4” d bar that came with the system but couldn’t accommodate a larger 1 -1/2 bar so I modified it. Also it wasn’t made to the tolerances that I needed so the bar across gets me level and a constant height. I always wax all the boring bar surfaces to keep them running smoothly including the trap, bar tool rest etc….
For the dimensions see the picture: I had to adapt the 3/4” posts to 1” to fit the Oneway banjos . I use the center post for most shapes that I turn. I can swing the banjos on the far side of the bed to get at the donut shape forms. Using The post that is 3” from the end is a great option for reaching in on these situations but you need an independently standing support for the trap. I use my portable table saw roller for this.
You asked about a weld vs the collar. The answer is a little complicated and for me it is situational and my preference. When I was choosing my third modification to my boring bar system it was to make larger forms in the space that I had my Oneway. I only have 2feet behind the bed of the lathe. So how deep can I really go was the question that had to be addressed. Some say the if I am hanging a boring bar 12” off the rest I need in theory 5x that amount on the other side supporting it. That’s 60” more from the rest. That’s a 72” bar. The diameter of the bar was another story. All this info is available online and in past articles in the AAW. Steve sinners double bar is supposed to be able to give you around 30” of hollowing. It weighs a ton but gets the job done. To cut to the chase, I was at the last KC AAW symposium and both steve sinner and Keith Clark had booths and were there. For me to hollow about 25” deep, I needed bars of multiple lengths to be switched as I hollowed deeper and deeper into the piece. Keith was willing to customize his system so we collaborated. In the end, I had many 1 -1/2” bars of different lengths so being able to use them with the home made welded motor collars made economical sense. I was using the Jamison-like d handle. My version was 17” long . I replaced it with a longer bar and a smaller 2nd bar connected by the collars. I think I saved money here. But if you have the room, the pocketbook and the strength to lift and push the heavy Sinner bars then do it. I would have if I had the room.
For the dimensions see the picture: I had to adapt the 3/4” posts to 1” to fit the Oneway banjos . I use the center post for most shapes that I turn. I can swing the banjos on the far side of the bed to get at the donut shape forms. Using The post that is 3” from the end is a great option for reaching in on these situations but you need an independently standing support for the trap. I use my portable table saw roller for this.
You asked about a weld vs the collar. The answer is a little complicated and for me it is situational and my preference. When I was choosing my third modification to my boring bar system it was to make larger forms in the space that I had my Oneway. I only have 2feet behind the bed of the lathe. So how deep can I really go was the question that had to be addressed. Some say the if I am hanging a boring bar 12” off the rest I need in theory 5x that amount on the other side supporting it. That’s 60” more from the rest. That’s a 72” bar. The diameter of the bar was another story. All this info is available online and in past articles in the AAW. Steve sinners double bar is supposed to be able to give you around 30” of hollowing. It weighs a ton but gets the job done. To cut to the chase, I was at the last KC AAW symposium and both steve sinner and Keith Clark had booths and were there. For me to hollow about 25” deep, I needed bars of multiple lengths to be switched as I hollowed deeper and deeper into the piece. Keith was willing to customize his system so we collaborated. In the end, I had many 1 -1/2” bars of different lengths so being able to use them with the home made welded motor collars made economical sense. I was using the Jamison-like d handle. My version was 17” long . I replaced it with a longer bar and a smaller 2nd bar connected by the collars. I think I saved money here. But if you have the room, the pocketbook and the strength to lift and push the heavy Sinner bars then do it. I would have if I had the room.
Dennis...thanks so much for the detailed description of your system and the picture with the dimensions. It is all very helpful to make a system that will work for me. My shop isn't very big but I have lots of room at the end of the Powermatic 3520 lathe. I will be heading to the steel company tomorrow to buy the steel tubing and shafting I need to make my system. I hope I can get the post welded accurately enough so that I won't need a leveler. I am thinking of putting a 3/16" metal rod along the centerline of the upper and lower tubing to reduce contact with the boring bar (1 1/8").
Cutters are another thing I'm trying to decide about. I think AZ Carbide's ProHogger and his negative rake carbide scrapper are worth trying. What do you use? Thanks again.
Before you go, how deep are you looking to hollow and what shape forms? One of the reasons I used a leveling bar on the trap, is that the square tubing was not true or the torque eventually warped it. I would go with larger than 1" and 3/16 and I would grind the surface true. My 1 1/2 bars are not pushing down on the trap, they are only preventing the rotation of the cutter. The force is resolved by the tool rest and the fulcrum device. You may be exerting too much force on the trap with your setup. Perhaps 1 1/2 or 2" squares 1/4 thickness would be stronger. There was a design by Brian Mcevoy that had a free standing trap for larger hollowing. If you can find info on that, it may be a better approach. I will answer the cutter on another response..got to run now
Opps..I had some typos in the above postings. My boring bars and shaft collars are not 1 1/2" in diameter. They are 1 1/4" in diameter.
@Brian Rohde :
"Cutters are another thing I'm trying to decide about. I think AZ Carbide's ProHogger and his negative rake carbide scrapper are worth trying. What do you use? "
I don't own ProHogger. But I browsed AZ carbide website and saw that it is similar to the Jamison swivel cutter assembly which I use a lot. I like using the 3/16 cutters HSS for roughing and the hunter 6mm round carbide cutter at 30 degrees for the last 1/2" of hollowing. I own the left and right-angle versions. I like the idea of taking small cuts with a small cutter when huge forces are in play when deep hollowing. Less is more here. In other words, I rather take a series of rapid small cuts than one big one with a larger cutter. I try not to put a lot of stress on the Log. That makes a lot of sense to me safety-wise. Also, I recommend gradually going up the ladder in project size and hollowing depth while you get to experience and test your new system and how the cutters that you try work. One comment on both AZ and Lyles's system. The Thorx screws and set screws always clog while hollowing. Where possible, I replaced mine with a hex bolt and/or deeper socket screws. The AZ proHogger round carbide cutter holder shaft is round allowing you different angles other than 30 degrees to try out. I imagine that may be an opportunity to experiment.
I will say in general in regards to woodturning, that "negative rake" to me relates to fine finishing with a burr and works well under certain conditions depending on grain orientation and wood density. Certainly not for hogging with a boring bar but for finishing a strong yes. You would have to try the tool and see if it works for you. For both scraping and hogging sometimes I use a tungsten
teardrop which originated possibly from Frank Sudol, an early AAW deep hollowing artist. It can be obtained from https://woodturningtoolstore.com/product/cutter-blade-for-hollowing-tools-2/. There are small and large versions. I own both. I favor this because it does not attach to your bar via a hole but it is slotted. You loosen it up and pull the cutter right and place it back in after sharpening or adjusting. You don't have to remove the nut and put it down somewhere and go sharpen. "Where did I put that screw??? or Opps I dropped it in the shavings somewhere." Saves you from these scenarios and saves time. Yes, you can grind the negative rake on it if you wish to try it. I don't cause the burr wears rapidly. Who is going to see the inside of the turning? I can get a fine finish that is smooth and pleasing to the touch using this teardrop scraper! Sometimes I use it as a scraper for hogging or for finishing. I leave its bevel at the stock angle.
For most of the hollow forms I do, about 90% of the cutting is accomplished with these 2 tools. I have a Dennis Stuart Curved bar that can accept these. The Bar is 3/4" and can fit into the Jamieson-like d handle or my 1-1/4" boring bar. I have selected 3/4" because all of Jamieson's bars will interface to it. I have selected 3/4" as my adapter because The Clark boring bars come with a 3/4" hole at the end. I bought a 3/4 to 3/8" adapter from him to connect the Jamieson Swivel. Jamieson Swivel can be removed and the teardrop can be used in its place! (see pictures at the end of my post: https://www.aawforum.org/community/threads/hollowing-system-boring-bars.13452/post-131514 ) The 3/4 hole was drilled approximately 4" deep to accommodate the adapters. He also has adapters for other cutters such as the very popular
Proforme Cutters. You can make your own adapters from 1018 steel rods to the size that is needed. I like the 3/4 size over the 5/8 because you can always adapt 5/8 tools with a sleeve. With 1-1/8" bar and a 3/4 hole still gives you enough steel(3/16" deep") for tapping some 10-32 set screws. This method makes cutter selection flexible.
I was curious, if you are using 1 1/8, how did you plan on attaching your cutters?
I don't know if Keith Clark is still actively manufacturing these days but his link for adapters is :
@Brian Rohde :
"Cutters are another thing I'm trying to decide about. I think AZ Carbide's ProHogger and his negative rake carbide scrapper are worth trying. What do you use? "
I don't own ProHogger. But I browsed AZ carbide website and saw that it is similar to the Jamison swivel cutter assembly which I use a lot. I like using the 3/16 cutters HSS for roughing and the hunter 6mm round carbide cutter at 30 degrees for the last 1/2" of hollowing. I own the left and right-angle versions. I like the idea of taking small cuts with a small cutter when huge forces are in play when deep hollowing. Less is more here. In other words, I rather take a series of rapid small cuts than one big one with a larger cutter. I try not to put a lot of stress on the Log. That makes a lot of sense to me safety-wise. Also, I recommend gradually going up the ladder in project size and hollowing depth while you get to experience and test your new system and how the cutters that you try work. One comment on both AZ and Lyles's system. The Thorx screws and set screws always clog while hollowing. Where possible, I replaced mine with a hex bolt and/or deeper socket screws. The AZ proHogger round carbide cutter holder shaft is round allowing you different angles other than 30 degrees to try out. I imagine that may be an opportunity to experiment.
I will say in general in regards to woodturning, that "negative rake" to me relates to fine finishing with a burr and works well under certain conditions depending on grain orientation and wood density. Certainly not for hogging with a boring bar but for finishing a strong yes. You would have to try the tool and see if it works for you. For both scraping and hogging sometimes I use a tungsten
teardrop which originated possibly from Frank Sudol, an early AAW deep hollowing artist. It can be obtained from https://woodturningtoolstore.com/product/cutter-blade-for-hollowing-tools-2/. There are small and large versions. I own both. I favor this because it does not attach to your bar via a hole but it is slotted. You loosen it up and pull the cutter right and place it back in after sharpening or adjusting. You don't have to remove the nut and put it down somewhere and go sharpen. "Where did I put that screw??? or Opps I dropped it in the shavings somewhere." Saves you from these scenarios and saves time. Yes, you can grind the negative rake on it if you wish to try it. I don't cause the burr wears rapidly. Who is going to see the inside of the turning? I can get a fine finish that is smooth and pleasing to the touch using this teardrop scraper! Sometimes I use it as a scraper for hogging or for finishing. I leave its bevel at the stock angle.
For most of the hollow forms I do, about 90% of the cutting is accomplished with these 2 tools. I have a Dennis Stuart Curved bar that can accept these. The Bar is 3/4" and can fit into the Jamieson-like d handle or my 1-1/4" boring bar. I have selected 3/4" because all of Jamieson's bars will interface to it. I have selected 3/4" as my adapter because The Clark boring bars come with a 3/4" hole at the end. I bought a 3/4 to 3/8" adapter from him to connect the Jamieson Swivel. Jamieson Swivel can be removed and the teardrop can be used in its place! (see pictures at the end of my post: https://www.aawforum.org/community/threads/hollowing-system-boring-bars.13452/post-131514 ) The 3/4 hole was drilled approximately 4" deep to accommodate the adapters. He also has adapters for other cutters such as the very popular
Proforme Cutters. You can make your own adapters from 1018 steel rods to the size that is needed. I like the 3/4 size over the 5/8 because you can always adapt 5/8 tools with a sleeve. With 1-1/8" bar and a 3/4 hole still gives you enough steel(3/16" deep") for tapping some 10-32 set screws. This method makes cutter selection flexible.
I was curious, if you are using 1 1/8, how did you plan on attaching your cutters?
I don't know if Keith Clark is still actively manufacturing these days but his link for adapters is :
Clark Deep Hollowing
The best hollowing systems on the market for wood-turning lathes which allows a turner to hollow beyond 20 inches deep. The system has accessories including laser and video thickness guidance as well as various cutters. Systems are customized to order.
www.theokspindoctor.com
Dennis...lots of useful info in your post on cutters. I got to the steel store today (8 degrees F and the wind was howling). In their outdoor cutoff pile I got 2 x 2" x 3/16" tubing (they had 1/4" thick 2 x 2 but it seemed like overkill), and some 3/8 rod to tack on the contact surfaces of the trap. I bought a 12' length of 1 1/8" cold formed rod and a 2' section to make posts from.
I will weld the 1 1/8" bars together, the longest will be 60" the shorter 48". They will be drilled to 3/4" as you suggest to receive
I worked with a machinist to make two 3/4" bars; one drilled to receive a 1/4 x 1/4 x 2 1/2" HSS bit sharpened to a point, the other has a flat on the end tapped to 1/4". He helped me make some teardrop cutters with slots and we hardened them by heating until they lost their magnetism and then quickly immersed them in oil. They are hardened (I tested with a file) but I can't get them to do what I intend. I wonder whether the fozen wood is a factor; all that I get is wet mush on the scrapper
In October I saw a demo by Peter Bloch who makes beautiful lampshades from Aspen. This is my objective and I'm trying to follow his lead in the way he makes them with some modifications. He has a couple of videos on Youtube that show the process. The end thickness is about 1/10" and he uses a tantung 1/8" flat stock teardrop cutter to make the final cuts on the inside and outside and uses a very soft touch to get very fine shavings as he approaches the final thickness.
I need no more than 24" reach into a wide opening. BTW...Peter uses a Dennis Stewart curved bar and one of his arm braces. I have both.
It is obvious that you have been at this for a long time and have solved a lot of problems. I appreciate your help.
Peter Bloch! I haven't heard the name in a while. Love his work and style. I never turned aspen. I am going to check out his You tube videos. Thanks for mentioning what you are doing. I did want to make some shades but I was going to hollow them out with a Hook tool. My initial thoughts were that Using a captured hollowing system may present some challenges but I'll watch the videos.
They are hardened (I tested with a file) but I can't get them to do what I intend. I wonder whether the fozen wood is a factor; all that I get is wet mush on the scrapper.
I don't know much about metallurgy. .I did watch forged in fire on TV. I never turned Ice or frozen wood either. So I can't talk intelligently about it. I'm assuming that it's frozen aspen. One thing for sure is that if it's frozen it probably will not crack until it starts to thaw. LOL I had a wet log in my trunk the whole winter that didn't check at all.
Lampshade turning is usually end-grain turning and hollowing. If you're attempting to go straight into end-grain, you're going to make powder in your ca0se mush. That could be happening. Also, turning ice must be really nasty on the teardrop tool. Resharpen and Go test it on some dry wood to see if its edge is holding up. What angle is the bevel on your tool?
They are hardened (I tested with a file) but I can't get them to do what I intend. I wonder whether the fozen wood is a factor; all that I get is wet mush on the scrapper.
I don't know much about metallurgy. .I did watch forged in fire on TV. I never turned Ice or frozen wood either. So I can't talk intelligently about it. I'm assuming that it's frozen aspen. One thing for sure is that if it's frozen it probably will not crack until it starts to thaw. LOL I had a wet log in my trunk the whole winter that didn't check at all.
Lampshade turning is usually end-grain turning and hollowing. If you're attempting to go straight into end-grain, you're going to make powder in your ca0se mush. That could be happening. Also, turning ice must be really nasty on the teardrop tool. Resharpen and Go test it on some dry wood to see if its edge is holding up. What angle is the bevel on your tool?
I'm fortunate that when I attended Peter's demo in October I learned that it would be his last and that after 30 years of making beautiful lampshades he was retiring.
My cutters are square as I thought the shear angle (about 45 degrees) would give me the clearance I needed. I've sharpened on a 80 grit, a 180 grit CBN, and I've tried honing with a ceramic hone and a diamond credit card hone. I'll try it on some dry wood. I tried my larger neg rake scrapper on the inside of the lampshade and all I got was mush. Following Peter's method I only plan to use it when I get near the finished thickness and with very light cuts.
I looked at Clark's website and watched a short video describing the rather complex mechanism for dealing with torque. Since you modified your Clark system to use double bars I assume it didn't work well for you.
I tried an Andre Martel hook tool and didn't like it at all. It took a lot of strength and tired me out in a short time. I also tried the shielded Munroe hollower II but it got clogged up. Steve Sinner suggested slowing the speed down but my friend took his tool away and I haven't been able to try it again. I hope the ProHogger will work for the hogging.
If you are ever in the SW NH area I will be glad to give you a section of big tooth aspen for you to make a shade. I'm using the smaller of the two logs I bought which was 14" on the small end.
You might want to try the Woodcut ProForme shielded hook tool for your lampshades. It is a bit tricky to set up but is very fast and clean-cutting. I find I spend as much time raking the long thick shavings out of hollow forms as making them, but it wouldn't be an issue for you.
I saw a demo by Peter Bloch some time ago, very cool. I intend to try my hand at lampshades myself when our logger pulls a couple of big popples out of the woodlot this winter.
I have the Clark system and it works well. It may have an advantage over the d-handle systems in that the "trap" is closer to the work and does not need to be moved as frequently for some forms. It does need a captured tool rest to keep the nose of the bar down as the trap swivels on a horizontal bar.
The Clark fulcrum that Dennis shows in post #13 is supposed to stiffen the 1 1/4" bar considerably for greater reach within a vessel. The fulcrum is designed to act as the toolrest with the reinforcing tube extending into the vessel. If a small opening is desired this would work better than a pair of bars side by side. For lampshades that would not be a consideration.
I have a teardrop scraper that was made with a hole for the attachment screw. A few minutes with a cutoff disc on a Dremel to make the hole into a slot was well worth the effort.
I saw a demo by Peter Bloch some time ago, very cool. I intend to try my hand at lampshades myself when our logger pulls a couple of big popples out of the woodlot this winter.
I have the Clark system and it works well. It may have an advantage over the d-handle systems in that the "trap" is closer to the work and does not need to be moved as frequently for some forms. It does need a captured tool rest to keep the nose of the bar down as the trap swivels on a horizontal bar.
The Clark fulcrum that Dennis shows in post #13 is supposed to stiffen the 1 1/4" bar considerably for greater reach within a vessel. The fulcrum is designed to act as the toolrest with the reinforcing tube extending into the vessel. If a small opening is desired this would work better than a pair of bars side by side. For lampshades that would not be a consideration.
I have a teardrop scraper that was made with a hole for the attachment screw. A few minutes with a cutoff disc on a Dremel to make the hole into a slot was well worth the effort.
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In this context I guess by shear angle you mean the cutter angle held to the wood, and since you said you use teardrp shaped cutters, the “cutters are square” means you have a 90 deg bevel on the cutter.
Holding the cutter at 45 to the work is perfect for a shear cut. If your bevel is 90, thats the problem. There has to be 7-8 deg relief angle behind the edge, meaning max 82-83 deg bevel max. Try a 70 deg bevel.
I have Lyle Jamieson’s system and swivel units, straight and bent, along with the #1 Hunter cupped cutter. It does very well with hogging end grain, as long as there are not really hard spots in the wood, such as oak knots and such. A freshly sharpened hss 3/16”x3/16” works better for hard gnarly grain. You need to move the cutter from bottom center, back toward you and to the outside - end grain cut direction is opposite facegrain.
Someone mentioned smaller cutters are better - I definitely agree. The larger scraper tips are very good for light smoothing cuts - I use the teardrop cutters from woodturning tool store as well as other shapes from other places.
I am also pursuing lamp shade making, and have been successful on smaller 7-8” dia x ~8” deep pieces. I’ll get up to ~14” dia x -12-15” deep probably, which is big enough for me. I didnt need the Jamieson rig for the smaller pieces - I hollowed them with a Ellsworth grind 5/8” shaft bowl gouge and did the finish cuts with various hand held hollowing tools I’ve made.
Last night, I saw about an hour of the Bloch Youtube up to the point where he has hogged out most of the interior and the cone was cut out that was used as a tailstock support. Now I have a better understanding of what you are trying to accomplish. Were you planning to use your new hollowing system to finish the piece at this point or where you planning to use the hollowing system from the beginning of the hollowing process foregoing tailstock support? (Tailstock would be in the way) if so, you probably would need a steady rest. Which brings up other issues.
I think the safest way with the least vibration is to follow Bloch roughing step. The large aspen log is conical in shape held by a 6inch faceplate at the shorter side with the wider bulky side facing the tailstock. In the demo, he was using relatively lite 60 lb log, but he said that some times his blanks weigh over 200 lbs. So getting rid of the bulk with tailstock support and then finishing off without the tailstock and using the boring bar would be less challenging. I don’t think the Jamieson or the pro holler will work as effectively as Bloch’s cutter that he ground specifically to hog endgrain. If you can, go back to the video or contact him to get the angles of the grind and use it. He said he used a specific steel from Germany but I’m sure you will get great results if you upgrade from HSS to Cobalt HSS steel. Somewhere down the line, I’ll grind one of these and test it out on endgrain hollowing. The angle was very severe maybe 20 degrees. The tool entered on an angle to the grain and was pulled towards the rim shearing off a lot of material. He said that he used a hand grinder to speed up the metal removal while forming the edge. Let’s talk about the tear drop cutter. It will not work as a negative rake scraper with Aspen cause it’s too soft. The grind only works well with dense hardwoods. It should work fine as a shear scraper as Bloch demonstrates.
I looked at Clark's website and watched a short video describing the rather complex mechanism for dealing with torque. Since you modified your Clark system to use double bars I assume it didn't work well for you.
There were 2 reasons I didn’t select that mechanism. ithe 1 1/4 bars would have a dado cut throughout its length which the mechanism attaches a ball bearing to stabilize the rotation. This is a very slick way of getting rid of the trap and the d-bar. A Hugh innovation in woodturning hollowing systems. However, I didn’t want to loose about 1/4” of boring bar mass and strength. The non-machined boring bars were cheaper. I replaced the mechanism with a small “fulcrum” Tube that allows the bar to slide like a piston in a cylinder. Instead of the small area of contact between the bar and tool rest, the small 4” fulcrum gives me that much more bar holding area reducing vibration and increasing bar stiffness. I have a second fulcrum the is 4” on one side and 12” on the other. The outer diameter of these tubes are 1 5/8” that really increases the effective diameter of the 1 1/4” bar. With both fulcrums in operation the 5 to one leverage over the toolrest ruleno longer applies. I can turn deep with smaller bars in my small room. The solution worked for me. The boring bar movement is smooth as silk. At times, I can hollow with two fingers. I can stand alongside the bed with this configuration not behind where there is only 2feet. I liked 1 5/8 minimum hole vs 2 1-1/8 or 2 1/4” for sinners double bar.
Re Andre Martel hook tool
I own them. He uses a tool rest with a moveable post that you leverage the tool into the wood which is capable of taking Hugh amounts of material. With a long bar the leverage makes the work much easier. For finishing endgrain, if used lightly along the interior of a shade, it can give a skew finish with little sanding.
Re: pro hogger
If your going to get the sinner bars which fixes your horizontal position, you may need to adjust your carbide cuter from 30 degrees so I would get the model that does this
Regards and good luck and thanks for the offer.
I watched the Peter Block 1-1/2 hr video. I had only seen a much shorter less detailed viseo of his work.
@Brian Rohde there are 2 concepts that can be followed to achieve hollowing large opening pieces: extended tool support, or stiff boring bars. Peter chose ext support, and that has been my choice, though I’m not trying to go 20+ inches deep.
A captive system is not needed. All cuts can be done with a straight bar with little to no torque induced. Using ext support, as Peter does, keeps extension off the rest to a minimum - interestly his use of a swan neck bar creates an issue, extended overhang. I suspect he started with a swan bar and didnt try a straight one, which would allow less overhang, reducing the vertical force component. Dont know for sure, as his hogging tool is used with a straight bar. I cant think of any reason a swan bar is better in this application.
His hogging tool bit is very interesting, and I will be making one to give it try.
An extended tool rest would be much easier to make and use vs a very large captive system. If you intend to do some deep hollowing through smaller openings, then a captive system makes a lot of sense.
On my next shade I’m going to use my Jamieson system (beendoing it all hand held). I want to see how well I can feel what is happening with the cutter during finish cuts, and whether I can do them better with the captive system vs hand held.
@Brian Rohde there are 2 concepts that can be followed to achieve hollowing large opening pieces: extended tool support, or stiff boring bars. Peter chose ext support, and that has been my choice, though I’m not trying to go 20+ inches deep.
A captive system is not needed. All cuts can be done with a straight bar with little to no torque induced. Using ext support, as Peter does, keeps extension off the rest to a minimum - interestly his use of a swan neck bar creates an issue, extended overhang. I suspect he started with a swan bar and didnt try a straight one, which would allow less overhang, reducing the vertical force component. Dont know for sure, as his hogging tool is used with a straight bar. I cant think of any reason a swan bar is better in this application.
His hogging tool bit is very interesting, and I will be making one to give it try.
An extended tool rest would be much easier to make and use vs a very large captive system. If you intend to do some deep hollowing through smaller openings, then a captive system makes a lot of sense.
On my next shade I’m going to use my Jamieson system (beendoing it all hand held). I want to see how well I can feel what is happening with the cutter during finish cuts, and whether I can do them better with the captive system vs hand held.
After pondering this for a while, If I was going to make a double bar, I think I would opt for a rectangular 'tube' and put a mount in one end for the cutting variations. Shouldn't be too difficult. Maybe I need to do more hollow forms...
robo hippy
robo hippy
Once again I want to thank everyone for their comments which are helpful to me. The blank I'm working on now is a "trial" and I'm not using tailstock support. I began it with an Andre Martel hook tool and tried a Munroe Hollower. My HSS with cobalt spear point cutters are working in a straight bar and then I used my D-way 5/8th bowl gouge with a fingernail grind and pull cut to reduce the thickness to 5/8". I can go thinner with that tool but wanted to be able to use the teardrop scrapper for the final finish and thickness. Peter Bloch's touch is so light that I don't think the curved tool is a problem though I have made a straight tool for the teardrop because I don't see any advantage to the curved tool. Like Peter I am using a heavy Oneway 6" faceplate and will use the tailstock on future blanks.
I'll try sharpening the teardrop scrapper with a bevel and see if that helps. Peter uses tantung for his cutters.
If you have made a lampshade I'd love to see a picture.
I'll try sharpening the teardrop scrapper with a bevel and see if that helps. Peter uses tantung for his cutters.
If you have made a lampshade I'd love to see a picture.
Like this? I welded 2 pieces of square tube together with a couple black pipe fittings to attaching the camera arm. Hardest part was turning the aluminum piece to attach my boring bars.
One of my test pieces. This is bradford pear, Its a light color wood I had available. The tenon is still attached at the top. Its ~ 8” x 8”, and ~ 0.080” thick. No finish applied. The lamp has a 60w bulb. It doesnt have the transparency really needed, but works for process development.
Very nice Doug. Did you use your extended tool support or the Jamieson system? What did you use to hog it out? BTW...Peter Bloch says it is easier to make a larger shade 12-14" diamter rim and the ideal depth is 10-12".
I used an ext tool rest - one of @robo hippy bowl rests he no longer makes. A robust J rest is similar. I hogged it out with a 5/8” bowl gouge with Michelsen grind, from center then up and out. For finishing the ID I Mainly used a 5/8” sq bar scraper tool I made that holds the bolt on scraper tip at 45 deg, inline with the shaft. Used a Sorby hss teardrop tip, 70 deg bevel, burnished edge. Might be easier to do a larger one - more room to work. Gonna try some sconces, or whatever they are called, for ceiling fans. They are small, ~ 4 dia x 4-5” long.
I have zero welding skills, so rather than welding 2 square pieces together, I would take one wider piece, like 1 inch by 2 inch, and then screw/bolt some thing on the inside for mounting cutters in.... Just thinking out loud....
robo hippy
robo hippy
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First Robo I'd like to say that double square bars will work but are very uncomfortable to use for very long. The first bar I made was square. I do a lot of hollowing some times I may spend a whole day just hollowing, didn't take me long to move to Steve Sinners bars. I currently have and use every size boring bar made by Steve Sinner and can say there a simple design that work excellent. Each size has it's limitations but will allow you to hollow deeper than any other design using the same diameter of bar. Full discloser I have worked with Steve in his Studio doing collaboration turnings & help him in his booths at sympoisums for the last 15 years.
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I'll tell you that they work extremely well. I've hollowed 600 plus vessels using Steve bars.
I had more luck yesterday hogging out the inside of the 14" diameter lampshade after I modified the HSS cobalt cutter I made by rounding the tip rather than having it a spear point. I used the bowl gouge with a fingernail grind and pull cut to reduce the walls to 1/2". Still no luck with the teardrop scrappers as all I got was a mush and no wisps of shavings. I had re-sharpened with a slight bevel. I don't want to go deeper until I solve the finishing cut problem to get the thickness to 1/8".
What does the “slight bevel” measure? Max is 80 deg to give enough clearance angle behind the edge. 60 deg will work fine. I use 70. Hone the grinder burr off, and burnish a burr.
Also, play with the angle of the top of the cutter to the wood - not the “shear scrape” angle, but the top to the wood. Tilting towards the wood, less than 90 deg angle, similar to a flat work scraper, can help. Try different angles to see how they perform.
Also, play with the angle of the top of the cutter to the wood - not the “shear scrape” angle, but the top to the wood. Tilting towards the wood, less than 90 deg angle, similar to a flat work scraper, can help. Try different angles to see how they perform.
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The bevel is 70 degrees. I sharpene on my 80 grit wheel and tried it, then on my 180 grit CBN wheel and tried and then I tried honing the burr off with a 600 grit CC device and then used a ceramic burnishing tool to create another burr.