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  1. #1
    Join Date
    Sep 2010
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    Lebrina
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    Default Home built toolpost grinders

    I have been pondering the subject of home built toolpost grinders lately, so I did the usual Youtube research and discovered that there are quite a few that have made toolpost grinding setups and these range from being very well executed https://youtu.be/znTTiDv02GM to useless deathtraps https://youtu.be/ExOk3vxIqEM
    My curiosity revolves around why nobody seems to be building larger toolpost grinders with the build quality of Stefan Gotteswinter's as shown in the first youtube link. It seems to me that it shouldn't be that difficult to build a machine with an induction motor somewhere from 1/4 to 3/4 Hp that would utilise either a 4-8" wheel or a smaller stone for internal work.
    I would imagine that bearings with the appropriate tolerance shouldn't be an issue and the machining seems pretty basic for anyone with a lathe and a mill.
    What am I missing?

  2. #2
    Join Date
    Nov 2017
    Location
    Geelong, Australia
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    57
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    2,651

    Default

    I think the difference is that there aren’t really any small ones available so people build their own. Larger ones, for the work involved it’s better value for most people to just buy a used commercial one for a few hundred dollars.

    Steve

  3. #3
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    72
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    Default

    Not missing anything. I'm building one using a 2Hp 30,000 rpm max brushless DC motor running on 18V. It's less than 50mm diameter and 85mm long.
    Trying it out with standard bearings to start with but expect to have to go to angular contact bearings to make it good....

    Cheers
    Joe
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  4. #4
    Join Date
    Jun 2012
    Location
    SA
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    1,649

    Default

    The problem with standard sized TPG's is that they really only suit a lathe larger than 10" swing to allow accurate centre line alignment on the toolpost top slide.

    So smaller home made TPGs are much more useful for smaller lathes. I have a Waldown 01, a 775 DC powered much smaller home made TPG, a tool post mounted electric die grinder, and a tool post mounted air pencil die grinder.

    The small 775 DC powered TPG gets most use as it is the most easily mounted and useful of the lot on my 10" swing lathe, for mainly model making work. It can also cross and radial drill as it has Jacobs chuck mounts.

    If you have a larger lathe and do larger jobs, then go larger if you want, but be aware tool post mount centre line issues may be a problem the larger you go.

    Cheers Rob
    The worst that can happen is you will fail.
    But at least you tried.



  5. #5
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Karl,

    Have a look at my "Brooks TCG" posts in projects. I'm currently on my third attempt to build one. Having had some issues with the four jaw chuck, and discovering just how difficult it is to get both end of the body truly in line. But like all things there is a learning curve.

    I'm currently making the end caps to screw in. Turning them to size is the easy bit.
    Best Regards:
    Baron J.

  6. #6
    Join Date
    Sep 2010
    Location
    Lebrina
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    Default

    Quote Originally Posted by OxxAndBert View Post
    I think the difference is that there aren’t really any small ones available so people build their own. Larger ones, for the work involved it’s better value for most people to just buy a used commercial one for a few hundred dollars.

    Steve
    Admittedly, I haven't looked too hard or for too long, but I have only seen one for sale in Australia and that was on this forum. As always there are plenty in the US via Evilbay, but they are typically 115V and freight is often greater than the grinder price.
    I can understand the issues around center height, but my new lathe is a 20" swing, so I've covered that issue at least.
    Based upon the unit that sold via this forum for $400 or thereabouts I think, you would definitely be better off buying rather than building, but my luck is usually to find the bargains just after someone else has.

  7. #7
    Join Date
    Nov 2007
    Location
    melbourne australia
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    3,228

    Default

    Quote Originally Posted by jhovel View Post
    ...2Hp 30,000 rpm max brushless DC motor running on 18V.
    That’s over 80A! What sort of power supply are you using?
    Chris

  8. #8
    Join Date
    Oct 2012
    Location
    Mullaloo WA
    Posts
    80

    Default Toolpost Grinder

    Checkout of YouTube a presenter Clough42 made one for smaller lathe.

    Col

  9. #9
    Join Date
    Dec 2013
    Age
    56
    Posts
    1,416

    Default

    Quote Originally Posted by Karl Robbers View Post
    Admittedly, I haven't looked too hard or for too long, but I have only seen one for sale in Australia and that was on this forum. As always there are plenty in the US via Evilbay, but they are typically 115V and freight is often greater than the grinder price.
    I can understand the issues around center height, but my new lathe is a 20" swing, so I've covered that issue at least.
    Based upon the unit that sold via this forum for $400 or thereabouts I think, you would definitely be better off buying rather than building, but my luck is usually to find the bargains just after someone else has.
    Not sure where your located but here is one

    https://www.gumtree.com.au/s-ad/mona...oid_VIP_sticky
    Using Tapatalk

  10. #10
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Karl you can get a very good surface finish using good quality standard brgs and a suitable shaft diameter on a tool post grinder.
    Making it rigid and getting the wheel close to the tool póst is important to not get chatter.
    When internal grinding depth of bore is limited to shaft and extension mandrel diameter, small dia shafts and grinding wheels chatter very easily
    so you can only do very short bores, when you get chatter if you are close to your target you will over shoot and throw the part over the fence.

  11. #11
    Join Date
    Jun 2012
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    SA
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    Default

    Quote Originally Posted by shedhappens View Post
    Karl you can get a very good surface finish using good quality standard brgs and a suitable shaft diameter on a tool post grinder.
    Making it rigid and getting the wheel close to the tool póst is important to not get chatter.
    When internal grinding depth of bore is limited to shaft and extension mandrel diameter, small dia shafts and grinding wheels chatter very easily
    so you can only do very short bores, when you get chatter if you are close to your target you will over shoot and throw the part over the fence.
    I don't know what you are doing wrong, but I have NEVER had chatter with any of my TPG's. TPG's after all are only kissing the work surface, so you must be really butchering/loading up the grinding medium to get chatter.
    The worst that can happen is you will fail.
    But at least you tried.



  12. #12
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
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    Default

    Quote Originally Posted by nearnexus View Post
    I don't know what you are doing wrong, but I have NEVER had chatter with any of my TPG's. TPG's after all are only kissing the work surface, so you must be really butchering/loading up the grinding medium to get chatter.
    Rob, if this https://www.youtube.com/watch?v=nHqHPGfgjuI is the extent of your internal measuring equipment then I doubt very much that you would know when you are getting chatter.

  13. #13
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    Jun 2012
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    SA
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    Quote Originally Posted by shedhappens View Post
    Rob, if this https://www.youtube.com/watch?v=nHqHPGfgjuI is the extent of your internal measuring equipment then I doubt very much that you would know when you are getting chatter.
    What the hell has that got to do with chatter ? Get real. You would see it in the grinding pattern first up and secondly it should NEVER happen given the very light pressures involved. LOL How much grinding have you actually done ?

    Just so we are quite clear on this, today I ground some 3 mm diameter shafts with my TPG. Try that with any sort of chatter.
    The worst that can happen is you will fail.
    But at least you tried.



  14. #14
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    Default

    Yes, the speed controller is suitable for 80A.
    I'm going to run it off an 18V battery.
    Just because it can draw that current, I doubt that grinding wheels in this application are able to absorb that sort of power. I'm also hoping to use it with burrs and small milling cutters. They won't use that sort of power either I suspect.
    I'll post pictures and more descriptive info when I've got it finished and tried it out.

    Cheers
    Joe
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  15. #15
    Join Date
    Aug 2015
    Location
    Melbourne, Australia
    Posts
    843

    Default

    Karl, I was pretty keen on building one - I even starting sourcing various parts - then a waldown c0 cropped up at a good price. done. ) I even picked up some small 11000rpm motors (as a lot of two) that might suit but they turned out to be 110v!

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