Chuck jaw boring

[precisionworks]

Hopefully this is the end of a long story ...

Bought my 14x40 lathe 36 payments ago & now the bank no longer owns it :D It came with a 3-jaw & 4-jaw chuck suitable only for selling so off to eBay they went. Picked up a nice used 4-jaw & then spent a ton of money on a Bison 3-jaw Set-Tru. The Set-Tru always runs within .0004" T.I.R. which is the accepted standard for this type of chuck but the grip on any smooth part has always been marginal. Quite a few parts have slipped in the jaws & most were not a big deal ... until a couple of weeks ago. A finished part was being threaded & the part was wrapped in a split brass bushing - refinishing that part after the slip meant that job paid negative $100 :shakehead

I talked with Bison customer service right after purchasing the chuck & they indicated that the very smooth grind necessary for small T.I.R. was causing the problem - like a dummy I believed that story until this week. I spoke with a number of chuck manufacturers & importers & all said the same thing ... the top jaws are not correctly ground. Phoned Bison CS again & explained the situation, they said after 12 months they would do nothing except sell me another set of top jaws for $237.80 + shipping & wouldn't guarantee that those would be any better. That seemed wrong so another call was placed, this time to the manager of CS. She said exactly the same thing & added that the next time I had a problem it needed to be addressed during the 12 month warranty. I told her that I'd never have a problem again with anything Bison since I'll never buy that brand again. Her reply is classic ...

Sorry about that.

I told her a few things that cannot be printed on a family forum, questioned her skills & abilities & suggested that she change her job title to Customer Service Avoidance Manager ... & hung up disappointed.

Seems like there are four options, all somewhat expensive.

1) Sell the Bison on eBay for half of what it cost & buy a Kalamazoo Micro-Set or similar. About $700 difference.

2) Buy the Bison top jaws & hope they are better. $250 there & iffy.

3) Find a chuck grinding shop, ship off the entire chuck with jaws, wait a month & be guaranteed a good result. $400.

4) Bore the jaws myself ...

The jaws run a bit over 65 HRc according to my hardness file test & in a perfect world they'd be reground with a tool post grinder. May do this eventually when my TP grinder gets put back together but for now a large boring bar with sharp negative insert is the best option. Running no more that 200 sfpm produces a nice cut, running over that makes a continuous red shaving.

The issue on in-shop boring is that the jaws must be pre-loaded & that means purchasing some type of boring ring. Dorian makes a really nice one for $899 & Ajax Tools sells an almost identical copy for $350 + $15 shipping. Called my old buddy Rocky at Ajax & managed to get the boring ring for $299 + $15 shipping. He said not to tell anyone except my friends on CPF :devil: (Call Toll Free (800)-543-5998. Monday - Friday 8-5 & be sure to speak only with Rocky).

Photos to follow but here are the instructions: http://www.kodiaktooling.com/pdfs/dorian_tool_lathe_accessories_catalog_page_88.pdf

 

[precisionworks]

This continues to get more interesting because Andrew Latawiec (previously in charge at Bison) is now VP at Global Tooling Solutions, maker of Gator (the new name for Fuerda) chucks. I'd spoken with Andrew some years ago, easy to remember his heavy Polish accent & he's really happy to be away from Bison because of "a number of changes that were taking place". Related my lack of customer service story & he assured me that will not happen with Gator & GTS as long as he's in charge.

Still planning to bore the Bison jaws to see if the grip problem can be fixed but the good news is that the Bison chuck can be pulled off the back plate & the Gator chuck will fit right on. Tools4Cheap shows a new Gator 8" Precision Adjust (identical to the Set-Tru) at $686.14 in the forged steel model (cast iron/semi-steel model is $250 less). Depending on how the boring comes out the Gator is looking like a good option.

http://gts-tools.com/gator-pa-series.html

http://www.tools4cheap.net/fuerda.php

Still planning to photograph the boring process so stay tuned.

 

[Atlascycle]

Good Luck Barry.

 

[andi15]

Hello,

Very nice story :shakehead

It should not be too hard to do that.
But I think grinding is far better than boring if you have hardened jaws (correct expression?).

Why don´t you make a "pre-louder" yourself?

Can you show us a photo of the chuck?


Fritz

 

[darkzero]

Sorry to hear that.

Ajax also carries Fuerda chucks, well that's who I purchased mine from & it was dropped shipped directly from GTS. Prices on them have gone up since though. Seen a couple people get the Fuerda 6-jaw chucks through tools4cheap. They look identical to the Bison 6-jaws. Fuerda also offers the adjustable 6-jaws in lower cost semi-steel where Bison does not.

Before I got my Bison I was set on getting a Pratt Bernerd but I wasn't able to get the adapter for months & I didn't want to wait at the time. Very nice chucks but quite a bit more than what Bison charges for theirs.

Curious, what exactly is causing the issue? The ground surfaces are ground too fine? So you will regrind with a coarser finish?

 

[precisionworks]

Remembered that my friend up the road has a Dumore tool post grinder with internal spindle - so the jaws will be done the correct way :)

Why don´t you make a "pre-loader" yourself?

They cost less to buy than to make when looking for an adjustable one. A CNC mill can do the scroll plate style but plugging in the X-Y locations of three arcs would be a pain, even if one were available to copy. The style I bought uses gears to evenly adjust the jaw pin locations & making one would take me a week or three. A lot of stuff is cheaper to buy.

Seen a couple people get the Fuerda 6-jaw chucks through tools4cheap. They look identical to the Bison 6-jaws.

They are 100% dimensionally identical & all parts will interchange, according to Andrew. Hmmmm, wonder where he got those prints :nana:

what exactly is causing the issue?

That is the million dollar question. Blueing a ground rod & turning it by hand in the jaws shows uneven contact at all three jaws & the contact is different on each jaw. Worldwide Chuck Repair said that there are at least a dozen factors in play & it may be just one or it may be a combination. They indicate every surface, blanchard grind everything, grind the master jaws to fit the newly ground jaw ways, etc. Half a day or more in the shop and about a grand. Makes a lot of sense on a 24" chuck but not on a small one.

IMO grinding the jaws under load will probably produce an acceptable result & the grip should be correct. But I have zero faith in it so it's on eBay as we speak, chuck only without backplate since the backplate will perfectly fit the Gator when the Bison sells. Priced at $579 OBO + $19 shipping. Current list price is $1128.05 at MSC, $1020.83 at ENCO. Any offer that's pretty close to $500 will be accepted.

 

[darkzero]

They are 100% dimensionally identical & all parts will interchange, according to Andrew. Hmmmm, wonder where he got those prints :nana:

:crackup:


So are you still planning to sell as is or will you be regrinding the jaws? Do you think/know if it has always had the issue?

I've seen people grind little chucks with a tool post mounted rotary tool but never the "correct way". I'm aware of the concept somewhat but never actually seen it done. Please post a few pics if you do!

How much difference is it in using an actual preload ring than using a self made one? Is it mainly just the hardness of it?

 

[precisionworks]

So are you still planning to sell as is or will you be regrinding the jaws?

It's currently listed as EBay item #19081740546. I would never sell it as is but will grind the jaws to perfection so the next owner will have no problems.

Do you think/know if it has always had the issue?

Since day 1 it's been the same. Bison CS stated early on that to obtain the T.I.R. the jaws were ground very smooth & two makers of aftermarket hard jaws said the same ... my mistake there for accepting that statement without third party verification.

How much difference is it in using an actual preload ring than using a self made one? Is it mainly just the hardness of it?

A shop made ring gives identical accuracy as long as the ring is smoothly bored but works only for that one ID. A person could do fine with one ring for grinding one chuck at one diameter but the purpose of multiple rings or a diameter adjustable ring is the ability to bore out soft jaws no matter what diameter is needed. Say the part is a rifle barrel from an M&P 15-22 and the diameter is .867" with a 2° taper - no easy way to grip that without boring a set of soft jaws to that diameter & taper. Just threaded two of those barrels & remember thinking "this is interesting" ... can't use the 3-jaw, 4-jaw or 5C so either turn between centers or bore out soft jaws.

Ring sets normally contain 36 rings like this one: http://www.smwautoblok.com/index.php/boring-rings-ads.html

A plate-style ring is another option: http://www.taiki-jaws.com/17-jaw_boring_rings.html

The gear drive ring is fastest to set up & costs not a lot more than the plate-style. I've been boring a number of soft jaws since starting barrel work so this ring will get quite a bit of use.

 

[precisionworks]

The more I looked at the homely old Bison the more it seemed like I should keep it. So ...

Opened it up, scrubbed it out & relubed. Trying to convince myself that even with zero factory support it's better than other alternatives.

The adjustable boring fixture is meant for flat soft jaws & not for step jaws so three adapters had to be made. First step was to plunge bore the bolt opening to .750". Jaws are over 65 HRc & the speed was set to 150 rpm to produce a surface speed of 29 sfpm. First tool was a radius edge solid carbide 4-flute mill followed by a square edge solid carbide 4-flute mill.

The factory bore (on the bottom) is rough but the new bore came out really smooth.

Then turn down the bolt heads to .500" to fit the .500" hole in the adapter, press the head into the adapter & silver braze.

The adapters come out even with the face of the jaw & allow the fixture to grip:

Bored the jaws using the 1.25" boring bar & they came out OK but grinding will be better:

Chucked up the 1.5" Thomson shaft & immediately noticed that the wrench went tight. Before it would go sort of tight, then the next pinion would tighten a bit more, then the next pinion, etc. Now any pinion brings the jaws closed & that's it. TIR after boring read .0004" without any adjustment of the Set-Tru screws. After grinding the TIR should be .0002" or less.

Time spent cleaning & greasing the chuck - 3 hours. Time to plunge mill the jaws & machine the adapters - 7 hours. Value of a chuck that grips as it should ... priceless :nana:

 

[wquiles]

Wow - lots of work, but now a keeper :)

 

[darkzero]

Wow - lots of work, but now a keeper :)

+1

Looks like it came out great & sounds like it did. I don't know but my instincts tell me to choose/keep a Bison over a Fuerda chuck any day despite the issue you had with yours. The Fuerdas look nice & I'm happy with my Fuerda 4-jaw for what I paid for it but it doesn't seem to have nearly the same quality as the Bisons. Perhaps Fuerdas keep getting better & Bison's quality are slowly becoming questionable? You 3-jaw looks very nice to me, even more now!

 

[precisionworks]

Thank you for your kind words Will & Will :)

my instincts tell me to choose/keep a Bison over a Fuerda chuck any day

This is purely speculation based on nothing quantitative but the people who run a company are responsible for both quality & customer service. When Andrew Latawiec ran Bison the quality was excellent as was the CS. How does a Bison Set-Tru chuck made today compare with one made under Andrew's watch? I cannot say. From my most recent experience with Bison CS it certainly seems like the bottom line is a lot more important than CS (or in this case BS). I've messed up more than one job for a customer & never even thought about saying:

sorry about that

That was the best & only response provided by the manager of CS at Bison Workholding. Pitiful or laughable, choose one.

I'm happy with my Fuerda 4-jaw for what I paid for it but it doesn't seem to have nearly the same quality as the Bisons.

I totally trust your evaluation. The Gator forged steel 3-jaw Tech-Tru (which so sounds like Set-Tru) is far less $$ than the equivalent Bison Set-Tru. $800 vs $1300, China vs Poland. If both had equal customer service the comparison would be much easier.

I won't say that Bison Set-Tru quality has decreased as I have no data to support that. And maybe my recent lack of customer service is an aberration that isn't representative of the company in general. Will I ever buy another Bison Set-Tru ... certainly, the day after Hell freezes over :devil:

 

[precisionworks]

Just slightly OT - got a package yesterday from Abbott Workholding containing three TG8MDS:

About as nice as any soft jaws I've ever bought & not expensive at $65 + shipping (10# total weight). These are Abbott's smallest machineable steel soft jaws (1.5" x 2" x 4") also available in aluminum, & they're a good general purpose shape that can be machined into lots of different configurations. You can machine a set of these from scratch but plan on spending some time to make a set of three that fit perfectly ... it's cheaper for me to buy a set, bore them to fit the part, run the lathe & bill out some time.

 

[KC2IXE]

Been a LONG time since I dropped by (change in work etc). Yes, the Bison Chuck sounds like it had issues, but working on small smooth parts after finishing doesn't sound like the job for a chuck at all, but a collet! A nice set Tue or better yet, spindle running collet setup can have TINY runouts (particularly spindle running), and grip TIGHT.

That said, I just scored myself a nice toy. I've had a lever collet closer setup for my Atlas Lathe for years (Yes folks, they are rare, but they were made), along with a full 1/64th set of collets in round, and a set of square and hex by 1/8" steps. The BIG problem on these old lathes however is the TINY spindle bore compared to newer lathes - 3/4", and with the collet closer in, 1/2" (UGH). Of course, my most common job requires 5/8" through spindle/ I finally got my hands on a Royal FRONT mount 5C collet chuck - a LEVER version of something like a Bison 5C collet chuck, so I can open and close the work while the lathe is running. JOY - I can do my 5/8" barstock job without stopping!!

 

[precisionworks]

... working on small smooth parts after finishing doesn't sound like the job for a chuck at all, but a collet!

Most small diameter work on either ground stock or finish turned stock is run in a Set-Tru 5C collet chuck. 5C collets stop at 1-1/16", ER-40 stops at 1", so everything larger is run in a jawed chuck.

Work that runs back into the headstock is usually run in the 4-jaw because it doesn't slip & TIR will adjust down to 0.000000" (just kidding, never have gotten it below 0.0001"). Longer work will be run in the Set-Tru 3-jaw once it's repaired.

The 3-jaw Bison Set-Tru forged steel chuck (their top model) is an equal opportunity destroyer of work. Any diameter slips as force is applied toward the headstock. Lots of good suggestions on my thread at PM: http://www.practicalmachinist.com/vb/gunsmithing/story-about-bison-fuerda-gator-chucks-263467/

A nice Set Tru or better yet, spindle running collet setup can have TINY runouts (particularly spindle running)...

The 3-jaw Bison Set-Tru has always run 0.0004" TIR or less so grip has never been a problem.

and grip TIGHT.

Collets, both 5C & ER, have a very short axial grip surface. On the 5C it's right at 1" long irregardless of collet bore. On the ER the axial contact is slightly longer. Short parts do very well in an ER or 5C but longer parts require a headstock spider for outboard support. The Bison Set-Tru in 8" diameter has more than double the axial gripping length & that allows running longer parts inside the headstock bore without having to set up & adjust the spider.

Should say it would allow this if it didn't slip on everything :(

The factory jaws had a very narrow gripping surface:

After boring the surface is much wider:

The 1" diameter Norton 38A stone came in so the Dumore TP grinder will be set up to final grind the jaws. Grip is vastly improved after boring & should be even better after grinding.

 

[KC2IXE]

I did say small smooth parts. I had gotten the impression from the thread that the parts were small enough for collet work, but I guess not, eh?

Yes, grip LENGTH is shorter, but grip AREA is a lot higher in collets due to there NOT being those huge gaps in the grip, sort of like you get a lot more grip area with a 6 Jaw vs a 3 jaw. Yes, grinding in is good. For that matter, you can get other brands of master hard jaws that might be 'better' out of the box, and of course, there is always soft jaws. The good part there is that whole part about the copper shims/split tubing. Machine up jaws out of the right material....

 

[precisionworks]

... you get a lot more grip area with a 6 Jaw vs a 3 jaw.

The pressure per jaw is one half in a 6-jaw & that's why they are popular for thin tube work. Grip area appears to be identical but perhaps someone with a 8" 6-jaw could measure that & post here. Either way it's the same amount of total gripping force spread over twice as many jaws.

... you can get other brands of master hard jaws that might be 'better' out of the box ...

+1

About $500 buys a very nice set of top jaws. One might think that a $1300 chuck would come with suitable top jaws without purchasing more or trying other sets or boring/grinding the jaws or ... :D

... there is always soft jaws ...

For specific shape or specific diameter work it's hard to beat custom bored soft jaws. For general purpose work step jaws are preferred.

 

[KC2IXE]

But the physics of friction will tell you straight out that by doubling the surface area, and at the same time halving the load per area, your friction which is what does the driving stays the same, BUT The shear forces which is what causes the metal to tear is halved...

 

[precisionworks]

It looks physically impossible to use 6 jaws that have the same contact area as three jaws IF the jaws are ground to grip small parts. Open the jaws to 1" diameter or 1.5" diameter & grind there - they'll never grip small diameter parts again but the surface area for gripping large OD's will be huge.

It appears the the six jaws have about the same contact area as three when both are ground from the factory to fit small diameter parts. The only practical way to increase surface gripping area in a jawed chuck is to bore pie jaws. Since pie jaws fit one size only they have excellent grip on that particular job. Step jaws they are not. Table below is from the Abbott Workholding website. Available in aluminum, CI & steel

 

[precisionworks]

Finally got caught up on urgent industrial repairs, cleaned the shop (as in 40+ hours of putting things away or throwing them away), did the taxes for 2011 & 2012 (yea, I know) & set up the TP grinder to finish the jaws out. First had to make a T-bolt to secure the grinder to the cross slide:

The thickness needed to be about .330" so I cut a piece of 3/8" A36 hot rolled flat bar & ran the face mill across it. Welded on a bolt & that's done.

Aligned the TP spindle with the lathe spindle & advanced the cross slide until there were sparks. Took the first grind at .004" DOC radial. Took another at .004" & then fed the carriage back & forth under power until the wheel sparked out.

The white 1" wheel is way up inside the chuck jaws.

All done & happy with the result. Total time to set up the TP grinder & finish the jaws was three hours. When the spindle is turning 75 rpm & the carriage advances .003"/rev it takes a while. Did finish two good books while the machine did its thing.

Chucked up the Thomson Linear shafting & dialed it in. Got it to run .0002" TIR (+.001/-.001) which is as good as I can do with the 4-jaw. The .0002" was measured both at the jaws & 5" out from the jaws - which indicates that the jaw contacts are finally co-linear (co-axial?) with the headstock bore.