Universal T&C grinder shortcomings

[John Stevenson]

Firstly this will be a double post due to the 4 picture limit in the web software and there are 8 pictures altogether.
May I ask that no one posts until the second post shows to keep continuity ? Thanks.

First of all my grinder is badged up as a ZZM but it's as close a clone to the Deckel as most.



I make no excuses for it's condition, it's probably 8 - 10 years old and has done good work but just not grinding end mills. It normally lives with a dished diamond wheel but for these shots I have replaced the original wheel which whilst worn, isn't worn that much. later on in pic 7 ? I have fitted a shallow diamond wheel to give an idea of the space saving.

All pictures are posed in that I have guessed angles but they will be within limits for the cutter. The cutter in the shot is an 18mm carbide on a 20mm shank, not the biggest in the box but big enough to show the problems.



This shot show the cutter presented to the wheel from the front. In this arrangement you can only get one angle which in this case it's probably the clearance angle for this cutter. There is no tilt adjustment on the collet holder setup in this plane.

The only ways to alter this angle is to raise or lower the wheel but that is not an option on these machines or to retract the cutter in the collet and in this case it cannot go back any further.

Now if we spin the collet holder thru 90 degrees and tip it up to use the face of the wheel we get this.



We have got enough room to get the cutter in and if we tip it more for the clearance angle we get even more room so it seems like it's the answer ?

However if we look at the bottom of the cutter we see this problem.



The inside radius of the wheel will hit the trailing tooth, on a 5 or 6 flute cutter it would be impossible.
On a two flute it wouldn't happen but you still have the length problem, this cutter was about maximum that would fit.

The answer is to tip the cutter the other way and grind the opposite tooth.

Continue to next post:-

[John Stevenson]

Second post:-

This is the cutter tilted the other way.



AS you can see we have tilted forward and run out of room. Another disadvantage of these machines is they are not designed to tilt forwards more than a few degrees, I think mine does about 15 degrees before everything gets egg bound.

This is the angle we are trying to get if the wheel wasn't as long or the machine was longer.



Fit a shorter wheel and we are nearly there.



The main problem for anyone wanting to use one of these for doing multi lipped cutters is the fact it wasn't designed for tilting forward.

Take a good look at the previous picture and this last one.



Note the blue marks ? the top left one is the centre of the spindle that secures the up / down adjustment block. the top right is the centre of the spindle that the collet head pivots on.

Now if the marks were reversed with the spindle behind the RH pivot you would get more room.
Another thing is when you tilt forward the lock for the collet pivot fouls the bed bar as seen clearly in the last picture.

If some care was taken to redesign the pivot and extend the collet holder slide it would make it a good tool for quickly touching up the ends of end mills.
I don't think it would be of much use to do flutes but as most wear is on the ends of cutters sacrificing a short amout of cutter will present you with a serviceable cutter again and very cost effective.

OK free for all now.

[hwingo]

John,

Thanks for posting these images and explanations. Aside from inherent limitations when grinding end mills, how has the machine served you when:

1. grinding points on drills?

2. shaping HHS and Cobalt lathe tool blanks for the lathe?

3. Sharpening previously shaped lathe cutting tools?

4. Cutting chip breakers in some of the previously shaped and sharpened lathe cutters?

5. Cutting away broken tips on Carbide lathe cutters and re-sharpening restored broken carbide tips?

I realize that much of this can be done with a simple bench grinder, BUT, some individuals may have physical disabilities and/or limitations that may easily prejudice motor skills. Physical insults limit dexterity when fine eye-hand coordination is required, e.g., prosthetic arms, missing fingers, muscle destruction, arthritis, poor eye sight or partial blindness. This machine may be a blessing to those with physical limitations.

Do you think this machine would improve "life in the Home Machine Shop" for those having the above physical disabilities?

While you are producing images, I would GREATLY appreciate your producing requested images regarding the subject you spawned in your post "Threading using a CNC machine".

Thanks,
Harold

[lane]

Just remember . Those type of grinders were never designed to do END MILLS. Single lip engraving tools.

[John Stevenson]

Harold,
1 & 2 Although the machine came with the attachments I have never used them.
Drills I free hand grind or use a dedicated drill grinder, lathe tools, again free hand or finish off on the surface grinder.

I accept this doesn't answer your question if you don't have the additional machines.

3 & 4 Again free hand.

5
Cutting away broken or damaged carbide tooling I use a diamond tile type cutter mounted on an angle grinder which in turn is fastened to a cheap snip saw type frame. this is the type of wheel I mean.

http://www.arceurotrade.co.uk/Catalogue/Diamond-Tools/Diamond-Discs-Burrs-Saw-Blades

Third one down, 100mm diameter.

Frame similar to this one.



THis makes a good job of cutting and bulk removal but leaves the edge friable so I then free hand trim on the Deckel clone with a fine diamond wheel.

[John Stevenson]

Just remember . Those type of grinders were never designed to do END MILLS. Single lip engraving tools.

Very true but with a bit of work they will do the ends.

[hwingo]

Just remember . Those type of grinders were never designed to do END MILLS. Single lip engraving tools.

Hi Lane,

Thanks for your reply. At this time my interest is really not with endmills. I am most interested in shaping and then sharpening HSS and Cobalt lathe cutters. Maybe an occasional re-construction of a drill point that's dull or chipped.

I haven't the faintest idea what a Single Lip Engraving tool is. What is this?

Harold

[loose nut]

Just remember . Those type of grinders were never designed to do END MILLS. Single lip engraving tools.

Single lip tools. Blah, Blah, Blah, don't say it can't be done, you just have to try harder.

[frankie]

I have a Universal T&C grinder Chinese of course, and with the use of a "saucer" wheel I have been able to put the secondary clearance on end mills, I also have used it to gash 4 flute end mills, however this kind of a dicey situation. Also I have been able to grind the O.D.s but was never able to do it consistently. Now having said all that I must also say that these grinders are very cumbersome to use for end mills, they work very well for single flute tools. I was walking around in a used machinery store a few weeks ago lo and behold a Cuttermaster grinder jumped in my truck so I took it home. It is very east to use for both O.D. and the end. I will probably will keep the Chinese grinder for a while but its residence in my toy room is rather iffy.

frankie

[frankie]

I forgot to say that the Cuttermaster grinder has a air spindle and that works as slick as snot on a doorknob.

frankie

[Arthur.Marks]

I haven't the faintest idea what a Single Lip Engraving tool is. What is this?

note: the above are milling cutters. They, of course, can also be used as lathe tools. It is a single edge milling cutter that has no helix. As an analogy, think of a D-bit in comparison to a 2-flute, helical flute twist drill. Same difference between a "single-lip cutter" and a typical 2 or 4 flute helical end mill you're used to using.

[lane]

Single lip tools. Blah, Blah, Blah, don't say it can't be done, you just have to try harder.

You don`t listen , I did not say you can`t do it. I said the machine was not designed to sharpen end mills . That explains what John was trying to show every one. Those are the problems you will have doing so .If it was designed to sharpen end mills it would be easy to do with plenty of travel to do so.

[loose nut]

Who isn't listening, your not paying attention to what people who support these machine say. Are they easy to use ,no. If it's all you got can it get the job done, yes at least to some degree. Most of use don't have access to the real deal, we have to make do with what we can. That's what these machines are about.

[Tony]

Excellent write-up, very clear. I think the ZZM is for left hand cutters thats why you're running out of space, you
should have gotten the MZZ for right handers.

[John Stevenson]

Excellent write-up, very clear. I think the ZZM is for left hand cutters thats why you're running out of space, you
should have gotten the MZZ for right handers.

You mean this one ?