I've enrolled in the @Mcgyver scraping correspondence course (read: I've purchased used HSM back issues where he wrote a multi issue guide). Not as good as hands on class with someone looking over your shoulder, but I'm looking forward to following his methods to see what I can accomplish at my typical glacial speed.
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TIR drift of Set-Tru Chuck
- Thread starter PeterT
- Start date
Former Member
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I know I was in it at the beginning in 1980 being taught by one of the initial starters of the Fully Scribe Round Notch Movement and one of the initial writers of these books.
IIRC, the series of books that my Father had (originally intended the house I now live in, to be Log, not framed) were by B. Alan Mackie. But the ideas have been around from far before him, and have been added to by far many after. I think Mackie was about late 1970's. But may be wrong.
It isn't, to be honest, new tech. Mostly rediscoveries of solutions long ago deemed appropriate.
Yes, I was referring to the ones in post 69. I never knew MS Office had crayons!
The bottom line is that I am always very impressed by how easily you add drawings and sketches to illustrate your thoughts. Despite my previous expertise in Catia, I am still old school. I usually grab a pen and paper, draw a quick sketch, and take a photo. Sometimes I might use the photo editing tools, or even sketch something on my phone and take a screen shot.
In my own defense, perhaps that's because using a PC is generally too inconvenient for me and I usually use my smart phone. It prolly has crayons too, but they are too small for my fat thumbs to hold.
All this is just my clumsy awkward way to both compliment you, and thank you, for taking to time to illustrate your thoughts so well for us. I wish we lived closer.
Dabbler
ersatz engineer
I agree. If the additional cost burden of a set-tru isn't a deterrent. go for it!
To be honest my current TOS 3 jaw chuck is good enough for what I'm currently doing. However I need to get in to production type work eventually. I think clamping the exact same stock (.575" A2 tool steel) thousands of times will eventually wear the chuck a little in one spot. All the parts require a .125" hole drilled through the entire length of the part. I also plan on doing a lot of different small parts that are small and it will be nice to have the 5C to grip them fast and secure.
The set-tru is within budget. I'm looking at the Bison set-tru and the bison back plate. Best price I have found is from the USA. They want $900 for it. A bit high but I should get a lot of use out of it. I already have a decent set of Lyndex collets.
No wonder you didn't get an answer to your question as fast as you wanted. You were not asking the same question.
This thread wasn't about a collet chuck, it was about a 6 jaw. Collet chucks are a whole level better because they don't rely on a scroll to evenly tighten jaws. They rely on a taper which is much easier to use repeatedly and reliably.
If you are gunna be making thousands of parts, and you have the money, by all means get the set-tru collet chuck and buy a box of the specific size collet that you need... Sooner or later your collet will be a bigger problem than set-tru is.
Also, get yourself a 12V milwaukee driver and grind or mill a few drivers to fit your chuck. Beats hand cranking that dumb T-Wrench every time you change the part. Or drop @a smile a note and beg him make you a custom spinner to fit your chosen chuck.
FWIW, I have a Bison 5C Collet Chuck. It never needed set-tru for any of the work I use it for and certainly not the kind of work you describe. Mine routinely delivers around half a thou concentricity even on a bad day.
Of course, if you have the money, then why not a set-tru collet chuck. If you want to save a little coin to buy more collets, I'd say you prolly don't need the set-tru.
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Actually, I think @PeterT was initially talking about his 5C collet chuck.
My bad. You are right. I just checked. The subsequent discussion about his 6 jaw prolly overwhelmed my 77 year old memory cells.
Might also be why @Upnorth kept waiting for an answer to a question we never got around to answering!
What was the question again anyhow? I forgot! LOL!
Doesn't change my opinion though - a 6 jaw doesn't have the inherent precision of a collet chuck and I don't think a collet chuck benefits from set-tru as much. I certainly don't miss it on mine. When I need better than my collet chuck can deliver, I don't wish for set true. I grab my 4 jaw or one of my custom spider chucks.
PS - Thanks for setting me straight.
You're both right. It was about Bison Set-Tru chuck drift (the title) & I referenced both my 6-jaw and 5C ST chucks at various points because they share the same mounting mode.
My prior Bison 5C non-ST (direct mount) chuck had runout of +0.0015" on its best D-pin orientation & so that was kind of the end of the trail. Getting a 0.0000" collet chuck out of the box is lucky, but I doubt that's typical & we can't count on that. I suppose you could regrind the collet seat if you had the wherewithal. Arguably might be a bit easier because you don't have to pre-load jaws, but seat grinding is still a precision job IMO getting the taper angle bang on over a very short distance, proper finish, taking off very little material & all the fun that goes with tool post grinding. Whereas with ST collet chuck you just dial it in to whatever it takes & good to go. They are basically like a 4J chuck in terms of adjustability, no reason why it cant be dialed into nil TIR if the need arises. If you don't require that kind of runout, repeatability, or the adjustability, ST is extra expense. Probably best to invest in other tooling that will benefit more.
As mentioned, collet chucks are kind of small diameter domain. If you need to grip >1.1" diameter precision part, a 5C is of no value so can't compare to any jaw chuck outside that range. Unless you buy a machinable (step) collet. But those are 'disposable' items & not exactly cheap. Actually very expensive for the good ones. Same goes for ID holding.
My prior Bison 5C non-ST (direct mount) chuck had runout of +0.0015" on its best D-pin orientation & so that was kind of the end of the trail. Getting a 0.0000" collet chuck out of the box is lucky, but I doubt that's typical & we can't count on that. I suppose you could regrind the collet seat if you had the wherewithal. Arguably might be a bit easier because you don't have to pre-load jaws, but seat grinding is still a precision job IMO getting the taper angle bang on over a very short distance, proper finish, taking off very little material & all the fun that goes with tool post grinding. Whereas with ST collet chuck you just dial it in to whatever it takes & good to go. They are basically like a 4J chuck in terms of adjustability, no reason why it cant be dialed into nil TIR if the need arises. If you don't require that kind of runout, repeatability, or the adjustability, ST is extra expense. Probably best to invest in other tooling that will benefit more.
As mentioned, collet chucks are kind of small diameter domain. If you need to grip >1.1" diameter precision part, a 5C is of no value so can't compare to any jaw chuck outside that range. Unless you buy a machinable (step) collet. But those are 'disposable' items & not exactly cheap. Actually very expensive for the good ones. Same goes for ID holding.
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Further note on potentially reconditioning a 5C collet chuck with unacceptable runout. In addition to the front taper seat dressing, also the cylindrical surface inside the chuck body, which mates the rear surface boss of the collet, which is supposedly concentric & a very specific annular clearance fit/tolerance. Not an easy job.
Stefan machined his own backplate with clearance specifically to allow adjusting for runout & just relies on the 3 front axial bolts to retain that position until such time it drifts or requires setting. Would not have thought would last very long but obviously it does. I don't see why one couldn't drill 3 more bolt holes between the existing, but not sure how much extra clamping pressure one would attain. I guess is why I always assumed the ST screws to be more 'permanent' but as discussed, maybe that introduces new self-inflicted variables.
Getting off topic & I know I've posted this before, but a good example of how not all Asian chucks (or machines) are created equal. Stefan's (6 year old video) looks pretty decent overall. James's (1 year old video) $150 is a different animal. It has a needle bearing in the nose. Not sure if that's a good thing vs ground thrust surfaces, but different. Many of his other surfaces are softer as evidenced by the dings & ability to file them. But have a look at that bevel gear grind job. The pinions are wearing out, probably trying to fight alignment. De-burring & grease is not going to fix this. I have some real nice Chinese tooling & some not-so-nice. Its often a bit of a gamble & price isn't necessarily indicative of quality.
I have a somewhat foggy recollection that mine was specified by Bison at 0.0006 and was actually better than spec by a tenth or so - but certainly not 0.0000.
I know I posted about it somewhere but can't find it. In the process of looking I found quite a few members with collet chuck runout in the 10ths.
Of course low collet chuck runout depends on low spindle runout. And low part runout also depends on good collets.
Anyways, all I really wanted to emphasize was that one can generally expect a collet chuck to be better than a scroll chuck. And depending on your needs, even a non-set-tru version might be more than enough.
I was going to write a fast response when I saw this answer. The first line of the first post is about a Set-Tru 5C collet chuck. Probably best that I didn't because it might have come across as me being a bit rude.
There are a couple of reasons why I like the idea of a set-tru. Main one is being able to dial out run out. Using a 4 jaw is my first strategy when I need something to be very accurate. Not a good option because the parts I make are made in sets of 27 parts. They all have different finished diameters and need to be within .001" O/D tolerance. They all start out being made with the same sized stock which is why the collet chucks are nice. I would waste a lot of time setting up the 4 jaw every time.
Second reason is I hope to be switching to CNC soon. It would be nice to be able to just swap the 5C from the manual lathe to the CNC one by just switching backplates. Not ideal but good for now.
No worries with me. I'd rather be corrected than leave a stupid answer laying there like a dead dog on the table. Not everyone has tough skin covered in thicker fur though.
Sounds like you have plan. You are lucky that way. Not everyone does.