Thread: Tool Post Grinders - Can A good one be made?

Simon
I dont think this will end in dissapointment. Just depends on how much effort you put into it. Just have to make it rigid enough. I'm sure there would be a wide choice of motors available. You could possibly even use an air die grinder as your motor. At least for an internal grinding spindle anyway. Keep in mind for external grinding you are not going to need the speed on the wheel that you would need for internal (smaller dia stone).
Go for it.
bollie7

Simon,

If you can buy one that works well, you should be able to make one that works as well or better, to suit your lathe.
Things to focus on are rigidity, good lathe bearings, rigidity, smooth grinding wheel drive motor/pulleys/belts (eliminate vibration), and also dare I mention it, rigidity.

Also helps to consider being able to grind tapers between centres without interference from the tailstock.

Good Luck.

Andrew

Hi Simon, I dare say that using the components shown, YOU would make a fantastic one. A WIP report is a must though.
I used a Dremel with a flexidrive, to get inside the ER25 collet I made, and it worked well, except that it wasn't all that rigid!! Wondering if one with a VS motor would be more beneficial, as that way for using small stones could be sped up and for outside work slowed down, either that or 2-3 speed?????
Kryn

My father made one maybe 40 years ago to use on his 9in Southbend. His had interchangable spindles for internal and external work, and was belt driven from a sewing machine motor, different drive ratios for the different spindles.

From memory, he used wheels abt 3 x 1/2 for external grinding, and points between 1/4 and 3/4 for internal work. The housing was similar to a couple of Waldown units that I recently spotted on ebay or gumtree, and the external spindle could be installed facing the headstock or tailstock to minimise interference between saddle and headstock/tailstock when grinding to the end of a workpiece. I presume that the internal spindle could also be reversed, but never saw it operating in that mode, which I suspect would be rather redundant.

The unit was rather underpowered but otherwise quite successful for my father's requirements, and was retained and used fairly regularly until his eyesight failed in his 80's and he stopped using the lathe. It is probably somewhere on the sunshine coast still, most likely rusting away in my BIL's wallless shed along with the rest of his tool collection.

Hi Simon

This was with my lathe when I bought it. I assume that it was made by the previous owner. It fits into the the four way tool post. It appears to have been well used, there are plenty of dings from the tool post bolts on the plate. Apart from the wiring the whole thing looks and feels good. The base is a piece of 1/4 plate with a stiffener welded onto the bottom. The spindle is held by a couple of machined ring clamps which are welded to the base plate.

It is a small universal motor, the wiring is very dodgy and apart from cutting the plug off I have never done anything with it. The DC motor that you identified looks like the go and if you do a WIP I will follow with interest and might convert it.

Let me know if you would like some more detailed photos.

Regards

Ian


IMG_0278[1].jpg

Hi Ian, I don't know about Simon wanting more pics of details, but I wouldn't mind seeing more details, PLEASE.

Thanks guys. More pics from Ian would be good! Don't get too excited about a WIP. 80% of my brain ideas end up nothing more than an idea, it's only a small percentage that actually get made!

But still, I am intetested in the idea of making one. Probably the hardest part is deciding on which S/H spindle to buy. The one I attached here is rated to 45K, that seems like way more than I need (on the surface) but when you calculated the required RPM needed to maintain say 5000 sfm it becomes clear that external grinding with a 75mm wheel requires about 6500 rpm, Thats pretty easy to achieve even I could make a spindle to do that. However, if I wanted to do some internal grinding using say a 1/2 wheel for a MT or something, the requires about 38K. Lets face it, the required sfm is achieved with a fast lathe speed since my lathe has a max rpm of 1500 rpm, so at max speed I would need 36500rpm.

I see some spindles are rated to 12K or 24K. Does this mean they came with a TP grinder that had maybe two spindles, one for internal and one for external grinding? If this is the case then would a higher speed spindle, like the one I attached (which is rated to 45K) be unsuitable for external grinding because it would be too small in shaft diameter, creating flex?

These are things I have no idea about and need to work out before I hand over my hard earned on parts for a project I will be disappointed in...

Just thinking aloud. I hope thinking is allowed.

Cheers,

Simon

Hello Simon,

I have a Dumore TPG. - https://www.woodworkforums.com/showth...73#post1254573 I don't use it for a number of reasons most of which are contained within that thread and a couple of related threads.

They are messy, the grinding less messy than the wheel dressing. This photo shows some of the wheel dust on the chuck and on the sheet of rubber covering the ways.




The dust is all pervading. I covered the entire lathe with plastic painter's drop sheets in a effort to protect the lathe. Operating the lathe while covered isn't really convenient neither is dismantling and cleaning the chuck and the saddle after grinding. The Hercus with its overhead drive is an awkward thing to cover properly, other lathes are probably easier to protect, that's if you are worried out protecting it.

I do have a Dumore manual that I can copy and send to you.

Interestingly, Schaublin among others, offered a selection of grinding spindles for their lathes. They were either saddle or vertical slide mounted and driven via an overhead pulley arrangement from an independent motor. Another problem with a tool post grinder is its physical size which on a small lathe like my Hercus, can obstruct vision and access. Schaublin's setup doesn't.

All that said and done, I have a second Dumore 44 that you can have if you are interested. The motor is rooted and I imagine the spindle bearings are no better. I bought it from the States, the seller describing its condition as "good" ( doesn't good come in all shapes and sizes!!! ). If you are interested I will snap a few photos.

BT

One of the first projects I started when I got a lathe was a tool post grinder. The bits I managed to make are still waiting in a box under the mill.

I presume your intention is to use a belt to drive the spindle from the motor and acheive the speed increase. When I looked at the motor, I thought it would make a perfect grinder on its own except limited to 12k rpm. It comes with an ER11 chuck to mount any wheel on a shaft up to 7mm diam.

I am thinking (yes, I think it is allowed) that I could buy one of these motors to use on its own as an external grinder and use the die grinder as suggested some time back by Nearnexus for internal work. This would be quick and easy, which is great in my case as I have a huge backlog of work to do.

On the other hand, you could keep looking and see if you can find a motor that will do both.

80% of my brain ideas end up nothing more than an idea, it's only a small percentage that actually get made!

You too. A lot of my ideas get started and put aside until later and when later comes, the situation has changed. I have many bits around that I know I cut up for something, but what? I also have many bits that I know what they are for. I have a plan to put these project bits in a 15l plastic bucket (I have dozens), label it and put it on the shelf. One of the issues here is that all my shelves are overflowing already. Another project that.

Dean

Originally Posted by Anorak Bob

Hello Simon,

I have a Dumore TPG. - https://www.woodworkforums.com/showth...73#post1254573 I don't use it for a number of reasons most of which are contained within that thread and a couple of related threads.

They are messy, the grinding less messy than the wheel dressing. This photo shows some of the wheel dust on the chuck and on the sheet of rubber covering the ways.




The dust is all pervading. I covered the entire lathe with plastic painter's drop sheets in a effort to protect the lathe. Operating the lathe while covered isn't really convenient neither is dismantling and cleaning the chuck and the saddle after grinding. The Hercus with its overhead drive is an awkward thing to cover properly, other lathes are probably easier to protect, that's if you are worried out protecting it.

I do have a Dumore manual that I can copy and send to you.

Interestingly, Schaublin among others, offered a selection of grinding spindles for their lathes. They were either saddle or vertical slide mounted and driven via an overhead pulley arrangement from an independent motor. Another problem with a tool post grinder is its physical size which on a small lathe like my Hercus, can obstruct vision and access. Schaublin's setup doesn't.

All that said and done, I have a second Dumore 44 that you can have if you are interested. The motor is rooted and I imagine the spindle bearings are no better. I bought it from the States, the seller describing its condition as "good" ( doesn't good come in all shapes and sizes!!! ). If you are interested I will snap a few photos.

BT

Hi Bob,

I read your thread when I did my search. I always attempt a search before starting a thread just to make sure it's not all been done to death prior. I noted that you had initial problems with your finish but you got it sorted with the bearing preload.

I camm appreciate the mess when grinding now that I have a sg, which I ALWAYS use with coolant as well. Wheel dressing causes more mess than I could ever have imagined. At least sg are designed for this and care has been exercised in the protection of their ways, not so with a lathe. Yes, I need to protect my lathe ways, it may be Chinese but it's all I have!

I certainly would be interested in some pics, at your convenience. No rush. As per my previous confession, many of my projects just never take off and the ones that do can sit for a number of (sometimes) years before I decide they are no longer a nice to have but now I need to have!

Hi Dean,

I'm glad I'm in good company with finished projects! My recent ball turner only took 12 months, but I knew it was there waiting to be finished. I just had it in a holding pattern. Actually, I now need it because my friend wants me to make him a new gear knob for his Patrol.

Yes, I have discounted the idea of a direct drive TP grinder eventhough there are a plethora of DC and other brushless types of motors with an included ER11 collet which would seem all too easy. However, I'm just concerned that the bearing quality and spindle design would not be condusive to the kind of finish I am looking for. There I think they may make a good drive motor but coupled to a dedicated quality spindle.

My other option, if I don't want to committ to a motor AND spindle is to just purchase a spindle and gerry rig a trimmer router I already have. It does 30K no load but with a speed controller could be made to any speed to probably 8K. It's small and has a collet which would make a temporary pulley fitment very easy. It's also compact and small and would be very easy to temp mount it.

Simon

Mate has an old Dumore 44 I can't see him ever using and might be willing to offload too - must be from the 30s or 40s going by the list prices in the box.

Originally Posted by Hunch

Mate has an old Dumore 44 I can't see him ever using and might be willing to offload too - must be from the 30s or 40s going by the list prices in the box.

Thanks for the offer. You can ask what he wants for it but if it's even reasonable then I doubt I can afford it ATM.

Cheers

Simon

Most of the Tool Post griders will come with a selection of drive pullys to achieve desired RPM.

Originally Posted by pipeclay

Most of the Tool Post griders will come with a selection of drive pullys to achieve desired RPM.

Thanks PC. I had noticed that. I also get the impression that to do very small internal grinding requires a very expensive and high reving spindle.

Another cheap option for a motor is this on ebay. I could even pick it up but for $15 delivery I probably wouldn't bother. Being a vacuum cleaner motor, I dare say it probably revs to about 12K and it looks like the air flow is from the front, meaning it would force air out the side rather than ingest grinding dust from the rear. It's only about 260W though. It looks old and it's made in Sweden, another reason to like it!

http://www.ebay.com.au/itm/291476689...%3AMEBIDX%3AIT

Simon