Grinding a bronze bush internally with a Waldown / Dumore TPG - how to do it
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- Опубліковано 29 вер 2024
- Tool post grinders are not actually the devil's children, despite what some paranoid lathe owners may tell you. A TPG can give superb symmetry if used correctly. Poor finish issues are dealt with in the video comments section.
Camera: Nikon L820
Hi Rob . I think a lot of people may use them once , get crappy results & put the thing back in the box again never to be reused ! You can achieve commercial finish & accuracy but there is a lot to learn to get the things to behave as they should . Flood coolant is your friend amongst many other things with a TPG ! Cheers .
Hi Max, yes you are probably right. There's an art to using one for sure. It's also getting very hard to get consumables in Oz. Brobo Waldown no longer supply or support Waldown TPGs. Dumore in the USA are really the only supplier of note these days and very expensive. Internal stones are the biggest issue. Cheers Rob
@@Xynudu Abrasiflex seems to be the best place so far , but with super limited range . ID is no problem but OD you have to pull a few tricks out of the hat to get good results from a harder grade wheel than what you want to grind with . I will be looking at getting wheels from the U.S soon , unless Norton can pull their finger out in Aust . The old supply / demand thing !
Hi Rob,
I do like these factory made tool post grinders... I like the design of the "TheMac J-3" one for some reason...
Pleased to see you got the results with your Dunmore.
Take care
Paul,,
Hi Paul, wow that's an expensive little beastie. Quality costs plenty these days. Cheers Rob
Have you ever tried to use a very fine burr on a tool post grinder for a job like this? If it works at all, it seems like it would be nice since there wouldn't be any abrasive grit to worry about on the lathe.
No. The finest burr would be diamond grit and that would work OK I expect. Mounting it is the issue.
Those are handy rigs Rob !!
They sure are Shawn.
I wonder if one of your lathe power feeds would provide a fully consistent finish on the operation. A carriage stop can prevent running into the chuck for safety. That grinder is of professional quality, superb.
Cheers
Hi George, yes you could use the power feed when grinding. It would have to be on a very high feed rate and you would need to have a reverse tumbler to change direction. There's no advantage really, as the stone width will always cause grinding overlap. Doing it by hand allows you to loiter on any high spots and vary the feed as necessary.
Waldown and Dumore are both industrial grade machines. Waldown no longer make TPG's, but Dumore still supplies and supports them.
Cheers Rob
NOTE: If you get a poor or irregular finish on your work piece it indicates YOU are doing something wrong or have set up the TPG wrong.
Visit the Dumore TPG trouble shooting web page to correct the issue: www.dumoretools.com/tool-post-grinders/trouble-shooting
Anyone that tells you these issues are normal has no idea about the subject.
Cheers Rob
You can here on the video that is hit and miss on the first few passes then near the end it is a continuous sound thanks for the great info and video
Yes you are right , only difference is 2 stroke cylinders ports will give standard interrupted cuts . I didn't mention 2 stroke but . Thanks
G’day Rob. The TPG works well, the operators not bad either:-)
Cheers
Peter
Ditto Peter. Cheers Rob
Hello Sir, l reproduced a tool post mounting piece for my HILDA like your design a while back. Only in one attempt , but maybe not such an accurate copy but it holds up well which brings me to the point . You would know if attempting to bore a small [70cc] 47mm one mm to 48mm is possible ? Similar China lathe, a jig to torque and mount in the 4 jaw, and TP Grinder for accuracy with less annoying spring from a long boring bar if possible ? $140 to get a good job by professionals would be my choice if it was a pricey build . Cheers
Hi John, it should be simple to grind out the 1 mm with the Hilda.
It's really no different to grinding lathe chuck jaws. You don't state the depth of the job ?
I would use a grindstone rather than a disc for that job, to counter any wear of the grinding medium (if the job is thick). For thin metal you could even use a diamond burr. Cheers Rob
@@Xynudu A grindstone was used for practice as you suggested , very nice finish and easy to hone finish . Thanks heaps , l am rigging an extension for my indicator to dial in more positions , do you have any tips in case I miss something ? Cheers
Hi John, I would always use a test indicator for this sort of work. When grinding make sure to start and work the grinding medium from each end of the job to counter any stone/disc wear and avoid a taper. Use the finest grit you can for the best finish and apply very light pressure to avoid uneven grinding medium wear. Check for any sign of harmonics pattern on the job which would indicate you have too much pressure, vibration, or grinder float. Lock down the cross and top slides if possible (use the gibb adjusters tempoararily if locks are not fitted). Cheers Rob
@@Xynudu Will do, much appreciated, Thanks ROB.
@@Xynudu Not sure if you received my reply so , thanks for the clever ideas and I will let you know if I succeed .
Couldn't you use that little gem to remove the weld bead from sections of pipe for your home brew aluminum (aluminium to you civilized folk, lol) round stock molds? Cheap way to add variety to your diameters of base raw stock
Yes you could.
Hi Rob ,
I would love a waldon grinder but every time i see one for sale they want too much money for it ! I have one that is made for my sieg c2 but haven’t used it yet . Looking at your set up and seeing the piece of cardboard or plastic you used as a cross slide screw cover reminded me of the stuff they made the polishing belt for a superfinishing machine out of and this then made me think of a cheap or free source of thin , flexible and durable plastic sheet - old X rays or MRI images suddenly sprang to mind - why i will never know , might need a few beers to work that one out 😀
Hi Ian, I think that clear film was plastic from a shirt box. It's stood the test of time well and keeps all the crap out of the cross slide opening. Cheers Rob
Very nice 👌 work.and good idea.thanks
Most welcome 😊
I just got one of these grinders too. Must get it out and have a muck around since i haven't used one since trade school.
Getting stones for them is the biggest issue these days - particularly small diam internal like I was using in the video. Cheers Rob
That's a great tool, got me thinking how I could make one 🙄
I made a smaller version using a 775 DC motor. It's very handy for small model making work. Plenty of people have done similar for all sized units. Good project. Cheers Rob
Terry, there is a really useful book on making precision rotary spindles for the home workshop. It is book number 27 in the Workshop Practice Series authored by Harprit Sandhu. Plenty of good guidance in it on producing a suitable spindle for a toolpost grinder. Costs about £7.50 GBP.