I bought a Vicmarc VM150 chuck to use on my new 25” lathe. What is the maximum bowl blank size can I mount using the VM150’s woodworm screw? I.e. when should I switch to a faceplate or faceplate ring?
For my first large-ish bowl I was starting out with a 12” x 3” block of a solid maple round that I picked up at Rocklers. (I just upgraded from a Jet 10-14 that I’ve used for the last 20+ years). It sounds like a woodworm screw is just fine, as long as I start with the tail stock.Too, it depends on multiple factors. E.g. What are you turning. Is the wood in good condition or punky. Well balanced or irregular blank. Can you keep the tailstock engaged. If you feel it's precarious, change your plan.
That said I have turned 12 x 12 x 6 well balanced, solid wood with tailstock.
A suggestion when using a screw chuck, don't use electronic (or mechanical) braking.
I’ve used the Nova screw many times without issue, but my bowls were limited to the size of my old 10” lathe. The Vicmarc VM150 screw is long, and does seam thin for its size… it protrudes 1-3/8” beyond my standard jaws. Hope to try it out todayI have used the same Nova woodworm screw for over 20 years. I have had 2 Oneway screws break and have never tried the Vicmarc screw as it looks to thin for me. I now always use the tailstock with the screw after having those Oneway screws break.
The Vicmarc VM150 screw is long, and does seam thin for its size… it protrudes 1-3/8” beyond my standard jaws. Hope to try it out today
Nice looking platter!If too long for a shallow bowl or platter, it's common to limit the depth by shiming between the chuck and the wood with plywood disk(s). But you prob already know that.
Was needed on this platter.
View attachment 78660
The screw for the Glaser screw chuck also seems thin but is tough, hardened steel and machined with quite sharp threads, nothing like the fairly crude threads on my Nova wormwoods. I drill a 1/4" hole the diameter of the central shaft and screw in the chuck in by hand. Holds incredibly well.
JKJ
How thick do you leave your bottom when you drill with the forstner?I never use a wood worm screw. I do have 2 5/8 inch forstner bits and drill a recess first and expand my Vicmarc chuck into that. Easier. Biggest I ever did was 22 inch diameter. I think I used the tailstock for that one. Most of the time, it is sufficient for blanks up to 14 inches, even 16 inch, but those don't sell for me. With any blanks under 14 inch, I never use the tailstock. That may be an "advanced" skill....
robo hippy
How thick do you leave your bottom when you drill with the forstner?
I was wondering about the center point of the forstner and how close the hole would get when hollowing the inside?
John, I am interested in your approach. Can you explain your method please. ThanksIf thickness is a problem, you can grind off the center point of a forstner bit and it will still work, easy in a drill press. I prefer to work in an entirely different way, but we are all different! (Yikes, what a concept!) . . . . . .
JKJ
The size itself is not limited. It is the weight and the balance that could give you issues, but those improve considerably when you use the tailstock.I bought a Vicmarc VM150 chuck to use on my new 25” lathe. What is the maximum bowl blank size can I mount using the VM150’s woodworm screw? I.e. when should I switch to a faceplate or faceplate ring?
Similarly, I will sometimes use a larger jaw set with the woodworm screw, e.g. 70mm, 100mm.I have lost a Nova screw once. Now I have made a series of backing plates 3, 4, 6" the slide on the worm screw. I find the extra flat backing area helps a great deal in stopping side movement which is a bit of a killer on screw chucks.
If thickness is a problem, you can grind off the center point of a forstner bit and it will still work, easy in a drill press. I prefer to work in an entirely different way, but we are all different! (Yikes, what a concept!)
John, I am interested in your approach. Can you explain your method please. Thanks
I do this as well, Forstner bit to 1/2" to 3/4" over Vicmarc shark jaws. The shark jaws give me a bit of flexibility if I want to re-orient.Sam, how deep I go with the forstner bit depends on if I am turning plates or bowls. With bowl slabs, especially ones I will core, I generally go 1/2 inch or so. Since bowl blanks can be a bit uneven when cut with the chainsaw, I drill so that the face of the blank sits on the edges of the chuck jaws, that flat outside where the chuck jaws come up. This makes the top side more even, and the bottom a bit wider. For plate stock, I might go down 1/4 inch which is more than enough to securely hold just about any plate I turn, which is up to about 12 inches. I have not really done any great big, like 16 inch platters. I might go a bit deeper for them, but again, the blank would be thicker. I would not remove the point in the center of a forstner bit. Mostly that is the marker I use to center the bit on the compass center point. I guess I could scribe a 2 5/8 inch diameter circle, but that would be an extra step in production that is not needed.
Is it just me, or do plate/platter blanks tend to get more harmonic vibrations than bowls?
robo hippy