# Worthy project or piece of scrap?



## Canadium (Oct 11, 2021)

I picked up this piece some time ago with the thought it would make an interesting project. Its an old Dumore 5-021 toolpost grinder. It was of course obvious at time of purchase that several critical parts were missing. ie toolpost mount, air filter, belt cover and grinding wheel cover. At the time I knew next to nothing about tool post grinders. Recently I finished some other all consuming projects and started to look at this one more closely. I discovered there are more parts missing than I had initially imagined. It originally came with a set of five different sized interchangeable pulleys for getting different speeds. My piece of course only included 2 pulleys. There were also several different interchangeable quills and spindles and mine again came with only one quill and one spindle and only one grinding wheel. No diamond dresser was included.

On the plus side the machine should fit my big lathe, the tool post mount and extra pulleys should be easy to machine although I'm not sure about balancing the pulleys. The motor brushes look to be in excellent condition. On the negative side I'm not sure if I will be able to fabricate or otherwise obtain the belt and wheel covers. Fabricating additional quills and spindles is probably beyond me at this time. Dumore has long since discontinued this model and it is not clear to me if parts on newer models are interchangeable with this one. Have no idea where I will get additional grinding wheels for it.

Would be very interested in other peoples thoughts/opinions about it.


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## Janger (Oct 11, 2021)

Home machinist mag had a recent article on home built tool post grinder. Author said to use skate sharpening grinding wheels. That might work for you.


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## Janger (Oct 11, 2021)

Good project. I’d like to see some more pictures. Especially grinding something.


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## CalgaryPT (Oct 11, 2021)

Very nice. Can you weld @Canadium ? You may be able to fab the belt and wheel covers if _exact replication_ isn't your goal. WRT to the belt cover the original part looks stamped, but I've made some replacement shrouds look reasonably close by doing them in pieces. I can more or less walk through the process I use. Haven't looked at the wheel shroud yet, but fab'ing these isn't as hard as it looks if you piece them. 

If you want some input, I'm happy to walk you through the process I use, with allowances for tools you either already have or don't have access to.

Fun project. Nice find


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## YYCHM (Oct 11, 2021)

CalgaryPT said:


> Very nice. Can you weld @Canadium ? You may be able to fab the belt and wheel covers if _exact replication_ isn't your goal. WRT to the belt cover the original part looks stamped, but I've made some replacement shrouds look reasonably close by doing them in pieces. I can more or less walk through the process I use. Haven't looked at the wheel shroud yet, but fab'ing these isn't as hard as it looks if you piece them.
> 
> If you want some input, I'm happy to walk you through the process I use, with allowances for tools you either already have or don't have access to.
> 
> ...



I this something you fabricated?


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## PeterT (Oct 11, 2021)

Dumore is still around but I have no idea if they are selling replacement parts.
https://www.dumorecorp.com/
The critical bits are probably the condition of spindle bearings & the belt. I'm guessing angular contact bearings or some kind of preloaded bearing setting & running oil bath in the cartridge. TPG belts are typically light weight flat style because high rpms are needed & there is a decent amount of power in the motor. Just as ballpark refernce, say 15Krpm on a 1.5" diameter wheel, 25K on a <1" wheel. So treat the belt condition with respect. There are a few forum guys who have Dumore's who hopefully will chime in. I would encourage you to think about an accurate means to infeed the TPG. Many people swing their compound at a shallow angle (which always seems to conflict with using the tailstock). But just as important, your lathe slides should be lockable  in position or else grinding to any tolerance is really hit & miss. There are lots of internet pictures with shiny parts, but I dare say a small percentage that hit a diameter to within half a thou. You also need a means to dress the wheel in-situ. I can show a pic of mine when the time comes.

Swapping pulley wheels usually occurs pretty much with every +/- inch wheel diameter (often) so consider how the belt cover can come on & off without a lot of fasteners etc. Here is how Themac does it.
https://themacgrinders.com/products/themac-j-45-grinder


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## Canadium (Oct 11, 2021)

CalgaryPT said:


> ... Can you weld @Canadium ?



I have a welder but I'd be lying if I said I can weld.


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## John Conroy (Oct 11, 2021)

I have a similar unit I bought at a garage sale years ago.  The previous owner said he used Honda timing belts turned inside out and there are some in the box. I have mocked it up on my cross slide and run it with the 2" grinding wheels but I don't have a diamond wheel dressing attachment and have never actually ground anything with it. The belts stay on the pulleys fine when it's running but there is no belt guard and I don't think there ever was. I'll probably never use it so if someone here wants it I think I paid $100 for it. You can still get the grinding wheels from Dumore but the ones in the box are Norton brand.


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## Canadium (Oct 11, 2021)

@John Conroy Nice! If I lived nearby I'd probably buy it! You even have the original box! I'd be interested in the dimensions of the tool post mount if that is possible.


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## CalgaryPT (Oct 11, 2021)

YYCHM said:


> I this something you fabricated?


Nope. That's an actual shroud from a Dumore Tool Post Grinder.


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## RobinHood (Oct 11, 2021)

I have a complete Dumore TPG in a box like Tom’s. There never was a belt guard. There is a wheel guard.

Flat belts are easy to get. I bought spare ones at Transmission Supply.

I have a lifetime supply of all kinds of different NOS Dumore grinding wheels.

Both the motor and spindle bearings need to be in really good condition for the TPG to work properly.  Everything (motor rotor, all pulleys, spindle & attachment components) is balanced to a high degree.

The tool post mount is easy to make - Domore pretty much tells you to make your own so that the TPG fits the lathe properly. For an air filter, get some fine mesh foam. The pulleys can be made relatively easily (every one of them is crowned), the problem will be balancing them. Same with the spindle attachments - especially the stuff needed for ID grinding with small mounted points; the speeds are > 20K rpm for the small stuff. Diamond dressing tool should be easy to make.

I can give you pictures/dimensions of all your missing components, if you want.


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## crittermutt (Oct 11, 2021)

I would be interested in buying it.


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## John Conroy (Oct 11, 2021)

Canadium said:


> @John Conroy Nice! If I lived nearby I'd probably buy it! You even have the original box! I'd be interested in the dimensions of the tool post mount if that is possible.



I can measure that tomorrow


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## trlvn (Oct 11, 2021)

VintageMachinery has manuals and other documents related to Dumore tool post grinders:

http://www.vintagemachinery.org/mfgindex/detail.aspx?id=2020&tab=3

Some of these have an exploded diagram and parts list.

Like you, I snagged an old, beat up TPG for cheap but mine is a Series 14 (little guy).  Dumore has some parts available but pretty expensive, especially with shipping to Canada.

My spindle needs work and I plan to see if I can mount a Dremel type chuck/collet.  If anything, I would be doing very little stock removal and Dremel-type wheels might do OK.  At least they're rated for the RPMs.

Craig


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## Canadium (Oct 12, 2021)

RobinHood said:


> Both the motor and spindle bearings need to be in really good condition for the TPG to work properly.  Everything (motor rotor, all pulleys, spindle & attachment components) is balanced to a high degree.
> 
> .



How would I know if the bearings are in good shape? Presumably if they are not there would be some rattling sounds when run? I just did a power up test to see how the motor runs. Made a temporary mount on my lathe. Didn't start at first because the wiring is buggered but that was easily solved. The motor is loud but there are no rattling sounds. More like a high pitched whine similar to a vacuum cleaner. Is that good?


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## Tom Kitta (Oct 12, 2021)

Same TPG went on auction for over 200 - so at 100 its like ... free. 

As for the project you have a spindle for it - so that is a good start. Usually on eBay small TPG go for over 300 plus shipping. 

I would make a mount for it and test it out - parts from Dumore are available but they are expensive as grinders usually costed a LOT of money in the first place. Heck that "scrap" you have is at least 100.


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## John Conroy (Oct 12, 2021)

I took a bunch of pics that include measurements  of the tool post mount. I've changed my mind about selling this thing, it's too cool to get rid of. Pics are posted here.

https://johnconroy.smugmug.com/Dumore-toolpost-grinder/n-dvbxh3


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## John Conroy (Oct 12, 2021)

Mine says no load speed on the motor is 16000 rpm and  sounds like a vacuum cleaner too.


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## Canadium (Oct 12, 2021)

John Conroy said:


> I took a bunch of pics that include measurements  of the tool post mount. I've changed my mind about selling this thing, it's too cool to get rid of. Pics are posted here.
> 
> https://johnconroy.smugmug.com/Dumore-toolpost-grinder/n-dvbxh3



Thank you John!!!


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## RobinHood (Oct 12, 2021)

As John states, yes, it does sound like a dyson.

If after running it for 10-15 min, that sound has not changed and the motor is not hot, then the bearings are probably still good. If the rpm starts to fall off and the motor seems to “labour“ as time passes, the bearings are overheating and are in need of replacement.

Now put a belt on it and do the same experiment with the motor driving the spindle. Look for change in sound over time, bearing noise and heat.

A good TPG will get warm bearings, have uniform sound and constant unloaded rpm. Any of these parameters run away on you, one should investigate.

I have ground 24+” long shafts, so the TPG was running for 3-4 hours straight, all parameters stayed constant, after they stabilized upon initial warm-up, for the duration.


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## Canadium (Oct 13, 2021)

So after input from @RobinHood I decided to do some more tests. Measured digitally rpm and temp during 15 min run cycle with and without belt. The motor is rated as 15500 rpm with no load and - surprise - my tachometer showed rpm very close to the 15500 mark even after a 15 min run time. The temp during this time only rose to about 38C from a starting point of about 25C. After another 15 min with the belt the temp rose to about 41.5C. Warm but not hot to the touch. Temp was taken near the bearing end of the motor body where the temp was the highest. The spindle did not get as warm as the motor body.

My conclusion is that the machine still runs reasonably well and is worthwhile fixing/restoring.


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## RobinHood (Oct 14, 2021)

I think you have a good motor & spindle combo.

So, yes, I would continue with the project.

You have probably already checked, Dumore does sell some parts for their TPG. Not sure if your model is compatible with a #44, but for the price they list the replacement pulleys at, you’d be hard pressed to make them yourself.

Here is the link:
https://www.dumoretools.com/parts/series-44-tool-post-grinders#1


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## Tom Kitta (Oct 14, 2021)

If you dislike the project you know you can easily sell it to someone else for good $$$


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## Brent H (Oct 14, 2021)

You can always bring it North of you a bit


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## Canadium (Jan 23, 2022)

Question for people with a similar old Dumore 5-021 toolpost grinder. I have over tightened the nut on the spindle pulley and am afraid I may be trying to turn it the wrong way. The similar looking nut on the motor pulley has a left hand thread (ie it loosens when turned clockwise). I assumed the over tightened nut on the spindle would have the same left hand thread but am not sure. So I would like to know how it is on your Dumore grinder. Does the spindle pulley nut on yours have a left hand thread?


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## combustable herbage (Jan 23, 2022)

On my themac the spindle is right hand and the motor is left hand if you know the motor thread the spindle should be opposite?
If you have the parts breakdown it might say left hand thread in the part description.


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## PeterT (Jan 23, 2022)

Hmmm... that probably explains why TPG motors are fixed direction, not fwd/rev. I always thought that was rather limiting from grinding standpoint. But upon further consideration, maybe not from a spindle or wheel nut unthreads at high speed & shoots yer eye out perspective.


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