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Worthy project or piece of scrap?

Canadium

Canadium

Ian
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.

Dumore2.webp
 
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.
 
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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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.

Fun project. Nice find :)

View attachment 17639
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I this something you fabricated?
 
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
 
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.





 
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.
 
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
 
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.

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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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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.
 
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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