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Discussion Starter #1
I roughed out two cherry bowls this morning. This is the first time I have used the worm screw in the chuck. The first one went without any problems. When I went to reverse the the second bowl I could not unscrew it. I had the spindle locked and the chuck unscrewed. I knew I didn't have enough strength to hold the chuck and un screw the screw. I took the bowl and screw out of the chuck and drilled a series or holes around the worm screw and then used a crescent wrench to unscrew it. The hole gave enough relief to free the worm screw. Has anyone else experienced this. I drilled a 9/32 hole. The directions said 7 to 8 mm. I set my digital calipers on 7.5 mm and then changed the scale to inches and that was 19/64". I guess I could have gone with 5/16"
Tom
 

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I normally lock the spindle and then I have been able to remove the bowl while on the lathe.

I may have had the chuck unscrew and likely used a wrench to remove with the blank off the lathe.

How deep was the worm screw? I only go about 3/8 in deep.
 

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Ive had to use the key to my chuck to keep the chuck from unthreading before. I dunno if thats a good thing to do or not but it hasnt caused any issues.
 

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Discussion Starter #4
Dave Paine said:
I normally lock the spindle and then I have been able to remove the bowl while on the lathe. I may have had the chuck unscrew and likely used a wrench to remove with the blank off the lathe. How deep was the worm screw? I only go about 3/8 in deep.
The vicmarc instructions said to drill the hold to a depth of 25 mm. I drilled it one inch deep. I don't believe I could have unscrewed it on the lathe. I was turning as hard as I could and nothing was moving until the chuck came loose.
Tom
 

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Discussion Starter #5
BassBlaster said:
Ive had to use the key to my chuck to keep the chuck from unthreading before. I dunno if thats a good thing to do or not but it hasnt caused any issues.
I tried holding the chuck with the pin for releasing it (to get some leverage) with one hand and trying unscrew the bowl with other. I just didn't have the strength to do it. It was that tight. The first one was hard to unscrew but not that hard . Also on the first one I did not have to hold the chuck as it did not attempt to come loose.
Tom
 

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The vicmarc instructions said to drill the hold to a depth of 25 mm. I drilled it one inch deep. I don't believe I could have unscrewed it on the lathe. I was turning as hard as I could and nothing was moving until the chuck came loose.
Tom
Wow, if you had the worm screw in 1in deep, I am not surprised you had a difficult time to remove.

Despite what Vicmarc said, try less depth, perhaps 1/2in.
 

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Discussion Starter #7
Dave Paine said:
Wow, if you had the worm screw in 1in deep, I am not surprised you had a difficult time to remove. Despite what Vicmarc said, try less depth, perhaps 1/2in.
Maybe I'm missing something but don't you want the blank to contact the face of the chuck jaws? Is that not what determines how deep the worm screw goes in?
Tom
 

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If you have a vice , clamp the screw shank in it (with timber jaws if needed) and wind the blank off the thread , if not , rig up something similar .
Has the screw hit a knot ?
 

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I have the Nova but they should be similar. I know Nova suggest a range depending on if the wood is dry or wet (smaller hole for wet wood). They also suggest lubricating the screw. A lot of people use a piece of candle and others use a piece of soap. Turn the lathe on and let a little melt onto or coat the screw threads.

I agree with Dave that 1" is pretty deep. I usually go 3/8 to 1/2" but longer should not hurt anything. For platters you may need to go shallow to conserve wood. You can make a spacer or two out of wood to shorten the length projecting.
 

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Discussion Starter #10
Manuka Jock said:
I don't think that the depth of the hole is the problem , its the gauge of the hole , the bit size . The bit is only half the thickness of the screw shank , callipers are not necessary , the naked eye can see that . How did you manage to get that wrong ? If you have a vice , clamp the screw chuck in it and wind the blank off the thread , if not , rig up something similar .
I did not measure the size of the screw. I converted from mm to inches for the size of the recommended hole. To check myself after your post I went on the net and found a conversion site. I entered 7 mm and the conversion was 9/32". Do you know something as to the size really needed for a vicmarc chuck? Is the vicmarc manual wrong?
Tom
 

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Maybe I'm missing something but don't you want the blank to contact the face of the chuck jaws? Is that not what determines how deep the worm screw goes in?
Tom
It may depend on the design of the worm screw and which jaws you use.

With my Talon chuck and No. 2 jaws and Oneway worm screw I get about 3/8in - 1/2in of the thread exposed beyond the face of the No. 2 jaw. I then screw down to the face of the jaws.

I have also used the worm screw with other jaws where the screw protruded full length and I used a spacer to control the length of the screw. In this case the spacer was limited by the small flange on my worm screw.

These days I prefer using the No. 2 jaws to mount and also control the length of the worm screw.
 

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Discussion Starter #12
Dave,
The first one came off OK. I did not have a problem threading either one on to the worm screw. I believe it would have taken a strap wrench to get the second one off if I had not drilled holes around the worm screw to get it to unscrew. The next one I will go one size larger on the drill bit unless someone knows that tho vicmarc manual is wrong.
Tom
 

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Maybe I'm missing something but don't you want the blank to contact the face of the chuck jaws? Is that not what determines how deep the worm screw goes in?
Tom
Yes you do want the top of the jaws in contact with the blank. But sometimes you can not, or do not want, to go 1" deep. I have a 3&1/8" forstner bit that I use to flatten the area for a screwchuck, faceplate, or other.

Almost any screw chuck you see in videos (even from the 80's to early 90's) the turner often uses a spacer to adjust the depth.
If you have not watched it here is a very good video by Mike Peace on holding methods (about 1.5 Hours). If you have watched it you may want to skip over to about 1 hr - 4 minutes and he talks about the screw chuck including lubrication and spacers.

I marked my spacers as most do by the amount of screw remaining. So, in your case, a 1/4" spacer would be marked 3/4", a 3/8" spacer would be marked 5/8", and a 1/2" spacer marked 1/2". Small pieces of plywood make excellent spacers as they are uniform and flat.
Nothing wrong with going the full 1" deep as long as you have the wood such as the interior of a bowl.
 

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Discussion Starter #14
Manuka Jock said:
If you have a vice , clamp the screw chuck in it and wind the blank off the thread , if not , rig up something similar . Has the screw hit a knot ?
It's no longer stuck. It was not stuck when I posted. I stated how i got it free. I just wanted to see if anyone else had experienced this problem
Tom
 

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Discussion Starter #16
NCPaladin,
Thanks for the tube link. I had not seen this one. I noted he did make a comment that sometimes the worn screw can be difficult to remove.
Tom
 

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I use Johnson's Paste Wax on the threads, but paraffin wax would also work to make the screw easier to turn going both ways.

The reason that the screw needs to be fully threaded into the blank is that not doing so can result in the screw tightening into the wood while turning and possibly slamming hard against the jaws.

The screw on a Vicmarc chuck is much longer than a Oneway woodworm screw. When turning especially hard wood, it is good to drill the hole slightly larger. If it is hard to mount the blank on a woodworm screw, it will almost always be twice as hard to remove it.
 

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I always drill mine at 5/16" and as deep as the screw. I've had a hard time with anything smaller so I stopped even trying.

I always use a little parrifan wax on the threads and remove the screw with a crescent wrench. I wrap my arm around the rim of the bowl, skin on wood is the best grip I've found, and get it free then it's easy.

I do like the idea of putting the screw head in my vise and turning it out. I will definitely try that one here soon.
 

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Discussion Starter #19
I will try a 5/16" hole the next time. The way I got it loose was quick and easy and did not hurt the blank as I got a rough turned bowl out of it.
Tom
 
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