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Unusual tool post grinder

B

Birkhoff

Active Member
I put this up on the Member Spotted forum but it is really more of a question than an advert. So this is a repost in a (hopefully) more appropriate forum. I'll delete the other one if I can.

I've been looking for a tool post grinder for my chipmaster on and off for a while. The lathe is a small centreline (5.5 inch UK/11 inch US) format so I don't want anything too clunky. This one came up locally a few weeks ago. Does anyone have experience with these or something like them? Variable speed, 45,000 rpm top end, apparently high precision. I assume this version is set up for a lathe; the company also made jig bore grinders that look quite different.

Any known reason why this would be a bad idea. It is on the small side for a TPG, which is a good thing.

Here's a picture from the listing:
 

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I think it will work fine. For the money I'd make sure it was working perfectly.
 
I'd take a pass. For internal grinding you need a longer arbor, and for external a larger wheel or you can't clear the tailstock etc. Even if you made a way to mount a larger wheel, it would be problematic slowing it down the required amount (you'll have no power left) and I doubt the spindle is sturdy enough for a large wheel in any event.

On of the biggest problems with grinding in the lathe in my experience is vibration. even the brand name stuff is frustratingly not smooth enough and its hard to get great results. ok results, but not great. Maybe this is the electric die grinder to beat all die grinders, but all the ones I've tried had a lot of vibration, so that would also be a big concern.
 
Mcgyver said:
I'd take a pass. For internal grinding you need a longer arbor, and for external a larger wheel or you can't clear the tailstock etc. Even if you made a way to mount a larger wheel, it would be problematic slowing it down the required amount (you'll have no power left) and I doubt the spindle is sturdy enough for a large wheel in any event.

On of the biggest problems with grinding in the lathe in my experience is vibration. even the brand name stuff is frustratingly not smooth enough and its hard to get great results. ok results, but not great. Maybe this is the electric die grinder to beat all die grinders, but all the ones I've tried had a lot of vibration, so that would also be a big concern.
Click to expand...
Ok this is terrific feedback (also, thanks David and Ironman). Not having done a lot of grinding at the lathe, I probably wouldn't catch this until later when I tried to do setup and ran into problems. According to google (practical machinist etc) these are legendary spindles for smooth operation, but only if in 'as new' condition and the high spindle speed could be, ironically, limiting. If I'm nearby, I may take a look at it, but as David says, this is a lot to pay for an antique that may be quite limited in use. The spindle is rated at 1/2 HP (other versions were 1/4 HP) so it still may have some grunt at lower speeds, but it is a very small rotating assembly for the torque curve. My first instinct is always to go the home-brew route. I have a small cordless trim router that I find myself grabbing more and more in preference to my corded tools. Probably about as accurate and smooth as anything else in that category, and easy to cobble together a mount.
Ironman said:
Just another idea for you. I don't often use it but it does ok, and I have a variable speed box I can use on it also
Click to expand...
So that arbor `extender' on the cutout tool -- is it an off the shelf item? I can fit a 1/4 inch collet in my drywall tool but extending that much mass out that far would not be my first thought . . . If it fits over the collet nut thread, that would be better. Then grind the collet end to centre. If you had a tiny grinder setup ;-)
 
Birkhoff said:
So that arbor `extender' on the cutout tool -- is it an off the shelf item? I can fit a 1/4 inch collet in my drywall tool but extending that much mass out that far would not be my first thought . . . If it fits over the collet nut thread, that would be better. Then grind the collet end to centre. If you had a tiny grinder setup ;-)
Click to expand...
It is a model DW660 and has a plastic skirt to vary the depth. I removed that and used it as a pattern for the holes in the mount plate. With the skirt taken off the extension is there as is. It now costs 125 bux at Cantire
 
Ah, I see. My drywall cutout is older, with no skirt so the collet nut almost meets the front bearing housing -- no shaft stick out to speak of. Thanks for the tip.

Edit: to correct stupid autocorrect
 
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I have more or less similar unit - you can get them off aliexpress for around 100 CAD or so...

As pointed out it is simply not sturdy enough - with larger stone you cannot even get close to high speed.

The power is not limiting factor - its the tiny spindle that cannot handle a lot of stuff.

I think for many things using air pencil die grinder will end up with more or less similar results as you have more or less similar spindle.

Overall tool post grinders are a real pain to use - setup, clean up etc.
 
I have used a Dremel flex shaft tool, held in my tool post, when I needed the capability and it saved my butt.

At that time, I had a Water Pump Bearing (water pump for a vehicle) that came with a shaft out both sides, and I needed to cut off the end that was in the way.

Dremel tool, a cut-off wheel, and a slow feed of the cross slide. Ten minutes of thinking, twenty more cutting the hardened bearing shaft off, and a $14 bearing that was actually in stock locally, fixed a waterpump that was a week's wait, and $150 that I could not afford at the time, to get...
 
Ironman said:
Just another idea for you. I don't often use it but it does ok, and I have a variable speed box I can use on it also
Click to expand...
Did you actually build that specific Dewalt version? I've had that one on my list for a long time. Between the top of the list and the end. It's not #42 but close.
 
jcdammeyer said:
Did you actually build that specific Dewalt version? I've had that one on my list for a long time. Between the top of the list and the end. It's not #42 but close.
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Yes, I built it using what I posted. It works fine, but I have not had luck in finding someplace stocking good stones lately. They all are mainly for hand held air gringers and are too course. It is in my lathe stuff and I have not used it in quite a while, I have not had jobs that needed grinding. Every now and then I see a real post grinder and want it, but I manage to talk myself out of buying.
 
Ironman said:
Yes, I built it using what I posted. It works fine, but I have not had luck in finding someplace stocking good stones lately. They all are mainly for hand held air gringers and are too course. It is in my lathe stuff and I have not used it in quite a while, I have not had jobs that needed grinding. Every now and then I see a real post grinder and want it, but I manage to talk myself out of buying.
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All I can find is this photo. No idea where the rest of the drawings are. I know I had more photos and the drawings.
ToolPostGrinder.jpg
 
I can send you what I have and some photos of my build if you send me an email. I found I had to change the mount a bit when I changed my QCTP to a C size.
 
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