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Do I really need a T&C grinder?

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bogstandard:
I have been asking myself this question for many years now, and would have jumped in with both feet if it wasn't for discussions with people a lot more knowledgeable than myself. Namely our own John Stevenson. I have discussed it a couple of times with John, and I think we have both come to the same conclusion.

It seems in the UK that people will go to great lengths to purchase a T&C grinder, and when eventually they do get one, 99% of them will only use it in it's basic format of grinding up lathe tools, twist drills and milling cutters. The rest of what it can do is just boasting fodder and would most probably never be used. Basically a lot of cash invested in a machine, that would easily buy and keep me in cutters for the rest of my natural.

So, I have my old surface grinder, and a load of 5c collets, what can they do for me?

I already use the grinder in conjunction with a small tilting vice, for grinding up perfectly shaped lathe tools, from normal cutting tools, to superfine parting and grooving tools with a tip only 0.020" (0.5mm) wide. So that is the lathe side sorted.

What do I need to do for the tooling I use on the mill? Basically, resharpen or rescue the end faces of standard cutters, or grind up a few special cutters that I may need. If the flutes require regrinding, then they would be thrown away, because as soon as the flutes are reground, it becomes a different size anyway.

Where is all this going you may say. Well, I have noticed for a fair while now, there is a little bit of fairly cheap kit that will do exactly what I want, using the machinery and tooling I already have.

http://cgi.ebay.co.uk/NEW-5C-END-MILL-SHARPENER-FOR-SURFACE-GRINDER_W0QQitemZ390043516415QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5ad067bdff&_trksid=p3286.m63.l1177&_trkparms=240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

During a Skype talk with Bob Deere, this item came up, and he said he has been using one successfully for a while now, and that he was happy with the results he gets. So as soon as the discussion ended, I went online and bought one. Thanks Bob for the info.
By the time the postage was added, it came to just under 55 squid. Bob did offer to buy one and send it to me, but there was no way he could get the postage any lower than was being offered by the seller. Again Bob, thanks for trying.

So this is what turned up today, eight days after I ordered it.
It is a reasonably made bit of Chinese tooling, with just a couple of minor imperfections in the design and build quality.
The first is that the locking screw uses a ball bearing that is pushed into detents around the rotating part, to hold the cutters in the correct relationship to the number of cutting faces (up to 12). Well the ball bearing falls out whenever the unit is taken apart. This will be given a permanent fix when I have time. The second minor annoyance is that the pins on the peg spanner won't fit into the holes in the collet locking ring. I will drill the holes out slightly larger in the future, as the collet can be tightened up enough by hand so it isn't yet causing a problem.




It works on the principle of two angled faces, and their relationship to the cutter face and the grinding wheel. The above picture shows the first angle it sits on, me pushing down on the end puts it onto the second angle, plus a side offset. Of course this is normally done by the mag chuck on the grinder.
The first face is used to grind the cutting edge, the second the relief angle.




"And how do you use it?" you may say.
I have absolutely no idea.
This is the shot of the operating instructions, the page on the left. It isn't even worth reading, as all it contains is a bit of Chinglish saying something about putting the cutter in the collet.




So armed with the fantastic operating instructions, I grabbed the most beat up, blunt and chipped tungsten faced cutter I could find (kept in the bottom of a box, in the hope of one day turning it into something else).
I dived onto the surface grinder, with the wrong, undressed wheel fitted (one for grinding HSS tooling), then setting it all up on how I thought it should go, I put the fixture thru it's paces.

The pic below shows it all. The one on the right is how it should be, a brand new metal shifting cutter.
The one on the left is my meagre offering after 15 mins playing about. Seeing this is the first time I had used it, and having no idea how to use it, it didn't turn out too bad. I assure you, that cutter WILL cut metal again.
I learned a lot, the correct angle of the cutting face to the side of the grinding wheel, and the depth of cut needs to be a bit deeper on the relief angle.
I can now guarantee, my 15 minutes of playing about, will ensure that the next cutter sharpened will be perfect.



Well that is one thing less I need a cutter grinder for, just need to get the drill sharpening bit out of the way, and I can forget about owning a T&C grinder forever.

Anyone got plans for a good drill sharpener that I can use on my surface grinder?

Bogs

BTW, if anyone is interested in the use of one of these things, I can easily make up and add on to this post, an article that shows just how to use it.
That shows just how easy it was to use, just 15 minutes playing about, and I am ready to put my reputation on the line.

Darren:
Please carry on John.....I have been looking at these, and T&Gs and a whole bunch of other stuff......

T&G's take a lot of cash for what they do as you say....if one drops on my lap then ok so be it, otherwise other ideas are the order of the day.

I was wondering if my Jones and Shipman vice could do the same job with a 5C collet fixture, it's just the indexing to sort after that.

I'm in great need of more info.... :thumbup:

sbwhart:
Hi John

I can see how it works doing 2, 3 or 4 flute cutters, but could it do a 6 flute ?

Stew

bogstandard:
I thought this might drag you out of the woodwork Darren.

I doubt if you would have such an easy time with trying to use your vice and a collet holder. I just don't think you will be able to hold rotational accuracy and presentation to the wheel.

I think this one could be fairly easily replicated.
 
In fact, for the price I paid, even with the crappy postal rates, it just isn't worth the trouble of trying to make one. I class my time now as worth 15 squid per hour to me, there is no way I could make one in four hours.

The way I looked at the overall situation was that a surface grinder is really a necessity in a precision workshop, more so than a T&C grinder, and because I already had everything in position, that automatically showed me the way I should proceed.

The money now saved on not buying a T&C grinder will go towards my dream of owning a small CNC mill, to help out with production work.
That is of course, if the better half doesn't find another use for the cash in the meantime. It all depends if I can find someone to do a weeks work for me at a reasonable rate.

BTW, to carry on from the above post, and Stew's question. I have only worked out at this time how to present up to four cutting faces, although it says it can do up to 12, it looks like any more than this might require a different shaped wheel, or a different wheel face approach method. I will need a little more playtime to solve higher numbers, unless anyone has done it before, and can give me a few pointers.

Stew, looks like the idea of bringing your old cutters along and having an afternoons resharpening session is now on the cards.

John

John Stevenson:

--- Quote from: bogstandard on July 08, 2009, 05:10:27 PM ---
 
In fact, for the price I paid, even with the crappy postal rates, it just isn't worth the trouble of trying to make one. I class my time now as worth 15 squid per hour to me, there is no way I could make one in four hours.


John

--- End quote ---

Get yer finger out Grandad,   :wave:  wait until I get back from taking the piss out of Darren's new Beaver mill this weekend and we'll see what can be done.

John S.

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