# About tool post grinders



## gadget_lover (Nov 15, 2004)

I have made a a couple of tool holders for the TS Engineering QCTP (for a HF 7x10 lathe). I bought a 60 degree dovetail mill which made my most recent attempt as clean moving and pretty as the store bought version.

So I thought I'd make a holder for a dremel tool driven tool post grinder. I have the basic idea, but there are a few questions and I'd like feedback.

I can make a QCTP holder that mounts directly to the Dremel or I can use a flex drive cable. I have a spare flex drive that I can donate to the cause. I also have an inherited dremel that I can dedicate. The flex can be closer to the tool post, but are there other advantages to either method?

My other query is exactly when would I want to use a tool post mounted grinder? I have read that abrasives near the lathe are bad juju. Can a tool post grinder do things that a mill does not do as easily?

Has anyone tried this?


Daniel


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## PEU (Nov 15, 2004)

Daniel, I had the same idea many times, and every time I concluded that the abrasive residue in the lathe ways is not a good idea. 

But if you only plan to use drills or endmills in the dremel thats a different story.


Pablo


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## McGizmo (Nov 15, 2004)

Daniel,
I would use which ever tool you think will be mountable in the most rigid condition. Abrasive grit should be flushed off the lathe I would think but if you look at surface grinders their ways are not dissimilar to those of a lathe or mill. /ubbthreads/images/graemlins/icon3.gif

I have an old tool post grinder I bought of Ebay as well as a drill holder that I made for my tool post and I have used both in the past. Neither the drill, grinder or the tools you are discussing are designed to handle heavy off axis loads so you need to go easy on your cuts. JMHO


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## tvodrd (Nov 15, 2004)

I frequently use pre-hardened, precision shafting at work for custom production equipment parts. You can turn it with carbide, but narrow grooves can be a a challenge. We have a Dumore toolpost grinder, but very rarely use it. For grinding retaining ring grooves we usually hose clamp the very tired Dremel to a tool holder block and go at it. Those little Dremel cut-off wheels work very well! You can cover the lathe's ways with a rag to minimize grit getting to them.

Larry


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## flyer91 (Mar 12, 2011)

Hi Daniel,

Not sure it this helps ..... but if not, maybe others might find it useful.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360237111217&ssPageName=STRK:MEWAX:IT

I just got one of these and they delivered in only a few days.
Could just make it yourself, but at this price why bother ...... :thumbsup:

Best regards,

Gary


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## precisionworks (Mar 13, 2011)

> exactly when would I want to use a tool post mounted grinder?


A ground finish is many times more smooth than a turned finish, so parts that have to fit together precisely are often ground. Motor shafting is ground, both for exact sizing & for a smooth surface for a bearing press fit.

When a dimension is critical, grinding to that dimension is much easier than turning or boring.

Some shop built TP Grinders here: http://www.cnccookbook.com/CCLatheTPGrinder.htm


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## Anglepoise (Mar 13, 2011)

Haven't seen a post from Larry for a very long time. Then I realized that the thread is from 2004.


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## unterhausen (Mar 13, 2011)

this is going to be fun for a while.

I made the mistake of buying a lathe that had been used with a tool post grinder, and it's a mess because of it. I suppose you should never buy a lathe sight-unseen anyway. I've since been told to avoid any lathe that has been used with a grinder, and I have to agree unless the cleanup was beyond spotless every time.


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## darkzero (Mar 13, 2011)

flyer91 said:


> Hi Daniel,
> 
> Not sure it this helps ..... but if not, maybe others might find it useful.
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360237111217&ssPageName=STRK:MEWAX:IT
> ...


 
I have a couple of those. To cut costs down, he now makes them out of aluminum & has them cut on a waterjet. Problem is, the sides of the shank that are cut of the waterjet are unfinished so using them as is can set the Dremel unlevel. Not that big of an issue but I milled them flat.

The threading on one of mine set the Dremel so the power switch was facing down towards the tool post which was anoying. But the seller was very helpful, checked his stock in comparison to a pic of where the thread started on mine & sent me another holder free of charge.

His older ones were steel which are probably more rigid than the aluminum ones but in a mini lathe (which is what I bought them for) probably can't tell much of a difference. Problem is Dremels have a plastic case. Since these are desinge to thread onto the nose end of a Dremel, it's not very rigid especially if you have a heavier size Dremel like my 8200. But again, it's for a Dremel using 1/8" bits so rigidity is not something that can be dealt with here. Plus grinding would only be done at small increments anyway.

Probably clamping the Dremel to a holder as mentioned might be stronger. Making a holder for one of those pencil air die grinder might work better, or better yet make a holder for a Proxxon rotary tool which have a metal case.


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## Clark (Mar 19, 2011)

I have put the Dremel flex tip in a V block mounted on the tool holder on the lathe.

If the Dremel is spinning the lathe is spinning, there can be very low tool force.

I don't think the bearings in the flex arm are as accurate as in some $1500 tool post grinder, but it goes fast like a tool post grinder, and some special things can be done inside flimsy parts.


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## radiator (Mar 27, 2011)

flyer91 said:


> Hi Daniel,
> 
> Not sure it this helps ..... but if not, maybe others might find it useful.
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360237111217&ssPageName=STRK:MEWAX:IT
> ...


 

Gary, thanks for posting that link. I'm pretty new to working with lathes, and have done some investigation of various schemes for setting up toolpost grinders, but had not run across that kind of adapter. It's an ingenious little device, isn't it...

As for keeping grinding debris off of the ways and out of the gearbox, I have heard that some people will drape some aluminum foil or similar material over the ways when grinding, so that (hopefully) the debris can be contained and easily removed when the operation is done. I have not done this myself, and I'd imagine that the downside is still that even with the best coverage, grinding debris, abrasive particles, and the like can be very small and can travel great distances and infiltrate holes and crevices in unexpected places.


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## 350xfire (Mar 27, 2011)

Little machine shop has some starting at $119 and up to $300 for the mini lathes that could be adapted, I'm sure:
http://littlemachineshop.com/products/product_search.php?critFast=grinder


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## John Hill (Jun 17, 2011)

I have a tool post grinder I made for my 12x36 lathe. I really only use it for hard materials.

The tool post grinder is really a finishing tool and cannot be expected to remove much metal.

Of course one should be careful with the abrasive dust on the lathe ways and the protection I used is sheets of news paper, or sometimes a cardboard carton cut and folded to catch the grit. Whatever you do, do not use rags as rags are dangerous near rotating machines and can easily drag you in or jam and damage the machine.


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