CNC Tool and Cutter Grinder

[awemawson]

For several years I've had the idea in the back of my mind to try and build / evolve / develop a CNC controlled Tool and Cutter Grinder. Indeed I've kept my eye open for suitable scrapped kit to act as a basis, but never actually  done anything about it.

Commercial machines control five or even six axis simultaneously, and 5 or 6 axis controllers are like hens teeth unless you are prepared to dip your toe in the EMC / Unix pot.

In an idle moment forced on me by the weather today I started doodling on paper, and it dawned on me that probably only two, or just maybe three axis need to move at the same time.

On the following doodle I can see that Wheel Elevation axis 'Y' and Wheel Approach Angle 'X' in most cases can be moved to a desired position for a particular operation, and then full control exercised over Tool Axis 'C' Tool Angle 'B' and Tool Traverse 'Z' reducing the needs of the CNC controller immensely. For instance a special 'M' code could be written to switch the three axis controller between group C,B,Z and group X,Y providing the mechanics and electronics maintained the axis in location after the switch over.

No doubt the programming would be 'interesting' and require many cups of coffee but the possibilities are endless. For instance, a sensor to scan the inserted tool, identify how many flutes, what helix angle etc to automate regrinding. Pipe dreams perhaps, but entirely possible I think.

. . . comments from you worthy gentlemen please . . 

[PekkaNF]

Have you read this one:
http://www.mech.utah.edu/~bamberg/research/PrinciplesOfRapidMachineDesign/Principles%20of%20Rapid%20Machine%20Design.pdf

Principles of Rapid Machine Design by Eberhard Bamberg

First it looks like has nothing usefull, but it very usefull indeed.

Pekka

[dvbydt]

From  many years in engineering, it is a lot cheaper and less frustrating, just to buy a new end mill. Regrinding the ends to get a sharp corner back is a fairly easy, straightforward job on a decent manual tool an cutter grinder with an indexer. Grinding the flutes is a whole new ballgame and if you can find an easy way to do this you will certainly be making a worthwhile contribution to our particular addiction!

If it helps, I am currently trying to build a simple tool grinder from an XY table - there will be no Z. Thinking about your proposal for the flutes  (I have some CNC knowledge), you will only(!) need to know - 1 an accurate zero. 2 number of flutes. 3 primary and secondary flute angles. 4 helix angle. 4 is usually to a standard. Using a flute finger as a rest was the manual way of virtually ignoring the problem. So on my simple machine when you solve all the stepper driver programming problems, a simple(!) stepper driven indexer would be relatively easy to add.

I will post my tool grinder and also some simple universal tool suggestions shortly. Your post has inspired me to start posting.

Good luck.

Ian.

[awemawson]

I agree - easier and cheaper to buy an endmill but that isn't the point - it's the journey that counts, including the ongoing learning.

(I probably have enough sharp end mills to outlast my needs until they nail my box lid down ! Added to which I have a Mk2 Clarkson T&C grinder, a J&S 1300EUIR cylindrical grinder with all the T&C grinder accessories and have disposed of two Quorns in the last few years)

[philf]

Have a look at this video:

Phil.

[vtsteam]

I agree - easier and cheaper to buy an endmill but that isn't the point...

 

[MetalMagus]

Hello,
Centroid do an 4 axis controller for around $1500 that is upgradeable to 8 axis. So maybe double the original price. But, the dreaded import tax will take that price up.

http://www.centroidcnc.com/centroid_diy/oak_cnc_controller.html

I suppose buying one or not will depend on budgets and the reality of cost versus requirements.

But, that controller does seem to have all the bells and whistles.

Cheers

Sean

[vtsteam]

You could do it with 3 stepper axes .... or even two, and an adjustment for depth of cut on the wheel. Controllers are like $20 on Ebay.

 

[sparky961]

I've been playing with an ANCA TG4, circa 1991 or so, for the past couple of months.  It has 4 controllable axes: A for rotation, X is left/right, Y is near/far, and Z is up/down.  Grinding spindle is mounted on Y-Z and has a manual rotation angle about the Z axis.  A axis is mounted on X.

All together it makes for some interesting motion possibilities.  I have electronic copies of the manuals if they'd be of any help to you.

[PekkaNF]

I've been playing with an ANCA TG4, circa 1991 or so, for the past couple of months.  It has 4 controllable axes: A for rotation, X is left/right, Y is near/far, and Z is up/down.  Grinding spindle is mounted on Y-Z and has a manual rotation angle about the Z axis.  A axis is mounted on X.

All together it makes for some interesting motion possibilities.  I have electronic copies of the manuals if they'd be of any help to you.

Trying to get my head about the axis...Is it like this, but grinding spindle is doing Y?




This looks pretty compact, and workpiece is easy to reach, but cartesians are all stacked:


Pekka

[vtsteam]

Hi Pekka, conceptually, take a lathe bed, add a  headstock and stepper driven spindle.

Add a carriage, leadscrew, and tailstock.

Drive the leadscrew with a stepper.

Add a grinder on a cross slide and way (and/or vertical way)  and ordinary grindstone, with axis parallel to the lathe bed.

You can either adjust its distance by hand wheel, or stepper drive it.

Total: two or three cnc driven axes. Lots of refinements possible, but in general, that's the concept.

As for the complexities of angles, helices, etc.for side dressing end mills .....in my opinion, that's what spreadsheet calculators do quite easily.

 I've written spreadsheets that output G-code for specific purposes.

[vtsteam]

ps. I like the M.C Escher machine base above.... 

[sparky961]

This looks pretty compact, and workpiece is easy to reach, but cartesians are all stacked:

The ANCA TG4 is in the configuration above.

[PekkaNF]

That is a very compact machine for the work envelope.

How easy it is to set up?

Pekka