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Hi folks,
Probably a silly question as I do not have other chucks to compare with.
Are lathe chuck jaws of the same size chuck (say 100mm 4 jaw self centering chuck from Rohm) the same? I'm looking to purchase those jaws which has a master and soft jaw on top (bolted on). Can't find information on the same chuck I'm using online to figure things out.
Wrote to Proxxon and they quoted me 2 brands: Mexpol and Rohm. I told them it's for the 4-jaw self centering chuck I bought from them.
Is it possible to make my own set of master jaws? How do I figure out the dimensions of the "patterns" that ride on the scroll if it says possible?
Thank you.
Wongster
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Maybe mill some precise shims to place over the jaws. Must say I never knew the was a self centering 4 jaw. I'm missing something I am sure, what is the advantage of a 4 jaw self adjusting over a 3 jaw?
So far as a pattern you have that, duplicating it will be some work.. I can tell you that.
Greg
Magazines have issues, everything else has problems
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Hi Wongster - not a silly question, but not one that I can answer for you. However, I do recall seeing a post or youtube video on machining jaws to fit a scroll. However, I cannot recall where I saw it. You could always aneal a set of jaws and then modify them to accept a soft jaw. I think that stevec may have done this in the past and posted it here.
Hi Greg - have you ever tried to grab square stock with a 3-jaw chuck? To do so, you need to find a section of pipe that fits, or bore one that will and then slit it. Then you can grab square stock in a 3-jaw. However, with a 4-jaw scroll, you just throw it in and tighten the jaws.
Hunting American dentists since 2015.
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Hello Greg and Mayhem,
Yes, so far the 4-jaw self centering chuck has been more a convenience. It may has its real place which I'm not aware of. Maybe better grip? Lol... I am just guessing. Since I had the 4-jaw for some square stock, I've not removed it and mount the 3-jaw. Both are Rohm chucks, very well made with very little run out.
Mayhem, Proxxon just replied to my email and offer a set of 4 unstepped and unhardened jaws. Pricey but will save me quite some trouble. The set, with estimated shipping from Germany and tax of 19% (I'm puzzled by this tax since I'm buying from overseas), will cost me around €130. She will come back with the actual number tomorrow.
Now, should I shorten the 4 blocks a little, drill and tap them so that I can make soft jaws of various geometries to mount on them? My initial plan was to just machine a v groove on them to hold rectangular pieces of pen blanks. Given their cost, I want to make them "do more"... lol.
Regards,
Wongster
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Having never used two-piece jaws before, I'll let someone more experienced respond. However, the ones I have seen used appear to have a raised key that runs perpendicular to the length of the jaw to locate the soft jaw section.
Hunting American dentists since 2015.
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One of my three jaw chucks has two piece jaws, wish they both did. As Darren said the permanent part has keys that mate with the top jaw to line it up and carry the load when bolted down. You could use them as is for now, machining what ever shape you need to hold things, when they start to get used uo machine them off and make top jaws to fit. The only concern might be that the teeth that engage the scroll might not be hardened and will wear quickly.
Free advice is worth exactly what you payed for it.
Greg
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(03-21-2017, 07:19 AM)Mayhem Wrote: Hi Greg - have you ever tried to grab square stock with a 3-jaw chuck? To do so, you need to find a section of pipe that fits, or bore one that will and then slit it. Then you can grab square stock in a 3-jaw. However, with a 4-jaw scroll, you just throw it in and tighten the jaws.
Must say no to that, cause I have a 4 jaw for that  , the more time I spend using the 4 jaw the better/faster I'm getting with it.
Do think the scrolling type will have the advantage if work requires removal. For a test fit and needs to be chucked for finishing. That could get a bit dicey with the independent 4 jaw if not paying attention.
Always good to find out about another way, for no other reason, but for the knowledge gained.
Greg
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The following 1 user Likes Vinny's post:
Wongster (03-21-2017)
4 jaw self centering chucks are popular with wood turners.
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The following 1 user Likes EdK's post:
Mayhem (03-22-2017)
If one can afford only one chuck, it should be an independent 4-jaw chuck. 
Ed
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Vinny,
Yeah I notice that wood connection when I looked the chuck up. I think carving new jaws would be a job. Milled alum shims and spot super gluing them to the jaw face would give him a soft grip he is looking for.
Greg
Magazines have issues, everything else has problems
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