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Black Eagle Precision tool post grinder

rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
I've been looking for a tool post grinder for my 10 x 20 Clausing. In the process I came across this:


Does anyone have experience with them? For the very limited use it will get, it looks as if it might be a better choice than a used Themac J35 or Dumore 14 from ebay.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
Looks like a router stuck into a QC toolholder. You can probably make one just like it yourself for a lot less. Run the router off of DC and get a PWM speed control and you'll have exactly the same thing.
 

Laurentian

Stainless
Joined
Mar 2, 2008
Location
Canada
Would be great for refinishing vintage motorcycle drum brake hubs ! Just make sure to clean up after, but I can see how that would wreak havoc on a lathe bed and carriage.. I like it, may consider getting one if our 60 year old Thermac isn't up to the task. Don't even remember ever even using it but should try soon on my old Yamaha YZ dirt bike hubs
 
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Terry Keeley

Stainless
Joined
Oct 18, 2005
Location
Toronto, Canada eh!

Looks like a one man band, no contact information - who knows if they'll be around in a week?

I have an old Series 14 Dumore that needed parts, gave them a call and ordered them...
 
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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Using that device I would add a C clamp to make it more secure. Then use something to make the OD near dead - square to the part to be ground, perhaps a strip of tape on the wheel's side and running an indicator down the length. perhaps run a diamond along the wheel side to true/dress the OD.
Grinding grit is terrible for a lathe so plenty of plastic sheets or whatever to keep grits out of the lathe works. A junk scroll chuck won't be made perfect by grinding the jaws. The excessive clearance around the scroll allows the center place to change. if it has .oo5 slop the part will run out .010. Shimming around can help, sometimes buying a new chuck is best.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
Using that device I would add a C clamp to make it more secure. Then use something to make the OD near dead - square to the part to be ground, perhaps a strip of tape on the wheel's side and running an indicator down the length. perhaps run a diamond along the wheel side to true/dress the OD.
Grinding grit is terrible for a lathe so plenty of plastic sheets or whatever to keep grits out of the lathe works. A junk scroll chuck won't be made perfect by grinding the jaws. The excessive clearance around the scroll allows the center place to change. if it has .oo5 slop the part will run out .010. Shimming around can help, sometimes buying a new chuck is best.

It won't cure all runout woes, but it can make a drastic improvement in many cases. Aside from that, it will do another important thing if done properly: remove any bellmouthing from the jaws. Wear in the chuck body or jaws can cause that, and resolving it makes a HUGE difference in how rigidly the chuck can hold work. I recommend using a Set-Tru mount at any rate if at all possible, which will solve any runout problems.
 

rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
Except for truing worn jaws I would never consider grinding chuck jaws. The design of a scroll chuck inhibits accuracy. The Set-Tru style is an improvement, but a 4 jaw independent is a better choice for accurate work. I've fount that slow to set up in the past, but with a half tenth indicator on a Noga holder I think it will be much quicker.

I saw a DG61003 at another PM member's shop and immediately ordered an NF61003. After seeing my NF61003 he's blaming me for wanting an NF61003 and I'm blaming him for wanting to also get a DG61003.

I've looked at the Dumore 14 and the Themac J2A and J35 grinders on ebay. All the ones I've seen so far were either pricey or in dubious shape. While parts are available for both makes, a bargain can become expensive quickly.

The big deterrent has been how rare one needs one. A number of sellers on ebay state that it sat on the shelf the entire time they owned the grinder. I've got a single spindle I want to grind. Other than that the only use I can see is touching up collets.

I may try the router since it's cheap. And I can always use it for woodwork, though I don't need another. I've also considered using a Dremel tool.

In any case it will be mounted on my QCTP so I can set it properly. I don't like the grit issue, so I'm looking into using diamond wheels instead.
 

Terry Keeley

Stainless
Joined
Oct 18, 2005
Location
Toronto, Canada eh!
Except for truing worn jaws I would never consider grinding chuck jaws. The design of a scroll chuck inhibits accuracy. The Set-Tru style is an improvement, but a 4 jaw independent is a better choice for accurate work. I've fount that slow to set up in the past, but with a half tenth indicator on a Noga holder I think it will be much quicker.

I saw a DG61003 at another PM member's shop and immediately ordered an NF61003. After seeing my NF61003 he's blaming me for wanting an NF61003 and I'm blaming him for wanting to also get a DG61003.

I've looked at the Dumore 14 and the Themac J2A and J35 grinders on ebay. All the ones I've seen so far were either pricey or in dubious shape. While parts are available for both makes, a bargain can become expensive quickly.

The big deterrent has been how rare one needs one. A number of sellers on ebay state that it sat on the shelf the entire time they owned the grinder. I've got a single spindle I want to grind. Other than that the only use I can see is touching up collets.

I may try the router since it's cheap. And I can always use it for woodwork, though I don't need another. I've also considered using a Dremel tool.

In any case it will be mounted on my QCTP so I can set it properly. I don't like the grit issue, so I'm looking into using diamond wheels instead.

Ever check the runout on router collets? I actually made one for my Porter Cable it was so bad, and that was a USA unit, not some cheap "quality offshore" POS. Also, that thing looks like it's held at only one end by an aluminum arm with a set screw, how rigid is that going to be?

$200 too much to spend for something that's actually made to grind hardened material and not cut wood? That will run smooth and has support?



"The bitterness of poor quality remains long after the sweetness of low price is forgotten.“

Benjamin Franklin
 

rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
Unfortunately, the Clausing 4902 is only a 10 x 20 machine. A 44 appears to be too big from what I've read.

By the time I consider sweat equity, the router would be $300+. It struck me as dubious, but it might be "good enough" which is why I asked if anyone knew anything about how they performed.

I'm going to save an ebay search on the small Dumore and Themac grinders and see what pops up.

I've seen some Dumore and Themac grinders small enough for the Clausing that were in nice condition, but they were upwads of $600.
 

ClappedOutBport

Cast Iron
Joined
Mar 30, 2016
I've used a couple Domores and a Thermac at work, and the latter is the only thing I would buy if I was in the market for one. Wow, it's so much better built and designed. I love the height adjustment, Domore is a joke in this regard.
 

cyanidekid

Titanium
Joined
Jun 4, 2016
Location
Brooklyn NYC
I'll agree with the assessment of others that TP grinders tend to be sought after and priced beyond their actual utility for most hobbyists. they have tended to think "well I guess I need one" after watching a vid of someone truing up a beat up chuck.

also agree that truing up a worn scroll chuck may not help that much. I have a stout Pratt Bernard 6 jaw "set tru" in very good condition externally, but when set at one diameter, it will be out 3-4 thou at other diameters, very disappointing! it doesn't seem to have enough wear to account for this, it might be a bad original grind of the scroll, or it was used for heavy repetitive work of the same diameter(s).

as to the re-purpose of a router motor or Dremel, there are a lot of good quality options between a cheap wood router motor or a Dremel, and a proper TP grinder. my first "TP grinder" was a Foredom #30 handpiece mounted in a holder I made for the toolpost. there are other quality handpiece type mini grinders and die grinders that make decent options for this. personally I wouldn't want to run a full size woodworking router on a lathe (kinda scary thought to me), and I wouldn't waste my time with anything Dremel.

Dumore even made a TP holder for their hand held grinders, so for a one-off especially I'd mount something along those lines. even a cheap air die grinder is a better choice than those.
 

rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
It's a small MT 2 taper spindle I" diameter and 7-8" long. Journals are about 3/4" wide.

The trim router is smaller than most of the Dumore and Themac grinders on ebay. From the photo it appears to be under 3" in diameter.

Cleaning up worn chuck jaws are more of a "while I've got it set up" side task. The only other task for it I can envision is touching up ER32 and MT collets. For that a die grinding handpiece would probably be more convenient.

I was taught that *no* scroll chuck was good to better than 2-3 thou unless it was a Set-Tru type and then it would only be true at one diameter. Otherwise, using a 4 jaw independent was more efficient if you were not turning a number of pieces the same diameter.

FWIW the damper in a Lacoste-Romberg airborne gravimeter has a pair of scroll form parts that must move freely nesting without contact. They don't rotate. A guy I talked to at a trade show where L-R had one on display said that they used that part as an interview question for a potential machinist hire. "How long do you think it would take to make this one part?" Most answers were 1-2 weeks. Correct answer was "one month". He said that no one realized how difficult it was to make. It also explains why a milk crate size box costs around 6 figures.

A land L-R gravimeter placed on a table would detect someone crawling under the table. The damper was there to deal with the airplane moving up and down. Developing that took decades of R&D.
 

rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
I picked up the HF Bauer label version of the router for $60. It's 10,000 to 30,000 RPM. The body diameter is 2.54" and weighs 2.9 lbs. I'm going to order some 1/4" mounted aluminum oxide points from McMaster-Carr to use with it. It's all cheap enough that I think it's worth a try. As numerous threads on PM note, TPGs are rarely used, but when you need one there are few alternatives.

When I bought my well used 10" x 20" Clausing 4902 25 years ago, my first project on it was an attempt to make an 18" test bar to check the tailstock alignment and straightness of the ways. FWIW my prior education was a Sear's 109 and a lot of reading. No teacher to guide me.

The effort failed badly because I didn't have an adequate appreciation of the amount of heat build up in the workpiece while turning without coolant. And I had no way to align the tailstock except to insert centers and try to match them. I failed and gave up, but only temporarily.

The attached photo is the bar which I fished out of the scrap pile and wire brushed to remove the rust.

Current plan is to rough turn the collars to <0.001" and then finish grind the collars with the improvised tool post grinder to a tenth. If I succeed at that I should be able to do my spindle job.

This bar introduced me to the problem of heating at a visceral level. But I don't know the solution yet. I know the bed has about 0.003" of wear in the middle from running the carriage back and forth with a 0.0005"/10" level on the carriage. So my assumption is the same as when I got the lathe and leveled it with a carpenter's level. Collars can be turned to diameter individually and then I can test the ways and headstock by indicating the collars from the carriage.

How should I deal with the heat? Less than 15 F temperature rise will blow out my desired tenth.
 

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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I don't see how that Multy step test bar will aid you very much. Having a test bar head-stock to tail-stock zero/zero at 20" out will not tell what the tail center height would be at 10" and 5" away from the headstock. You suggest that the bed may be .003 low in someplace.

Still, likely you will wish to grind the device with the OD of a grinding wheel so it would be good to find a suitable wheel that is larger the then diameter of your grinder so you can make the part OD with the wheel, also that the wheel can run at the RPM of the spindle/motor.
46K may be ok..54 and 60 may prove a little hard (wet may be ok)
Yes, you can kick the motor at an angle and dress the wheel flat to the part,
Grinding takes a lot of pressure so good to have the grinder holding fixture strong enough to take a 3 finger push.(2 fingers push minimm.)
 
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michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Yes, I sent that guy on eBay a message that selling wheels in the USA not including the RPM is leaving him open to a law suite.
A vitrified wheel should never be mounted with not having a blotter..That eBay guy does not seem to offer a blotter or mention them.
Yes, a 3" grinding wheel can kill you.

wheels are tested to + 50% RPM to see they will not blow up..and each production run of wheels is also tested to be sure something in the mix has not changed.
Likely a guy who knows nothing about grinding selling wheels.
 
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rhb

Aluminum
Joined
Apr 27, 2019
Location
A small town in central Arkansas
If all the collars are the same diameter and you adjust the tailstock so that the collars at the headstock and tailstock read the same horizontally and vertically, you can measure the deviation along the bed with an indicator mounted on the carriage.

It's true that won't measure the tailstock ways, but once you know the carriage way profile you can indicate the tailstock ways from the carriage and a bit of arithmetic will give you the tailstock way profile.
 








 
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