The Shop > Tools
Show us your T&C grinder set ups
RotarySMP:
I know tool grinding is one of those 5 minute jobs, to get another job done, but it would be greatly appreciated if the experienced guys could take a photo or two of their set ups and post them here.
I got a Clarkson MK1 T&C Grinder last week, and just got the 3PH power where it stands, so after grinding a few drills with a cheap and nasty drill jig, I thought I'd better try and sharpen up my extensive collection of blunt end mills.
I have the Clarkson guides from Steven:
http://www.bedroom-workshop.com/grinder-clarksonbooks/0grinder-clarksonbooks.html
Page 10 of the 1971 pdf.
but for a rank novice like me, the instructions are obviously not basic enough.
Searching the web, there really isn't that much information about the nitty gritty of using a T&C grinder. Overview yes, but details are thin.
For this case I have the Universal head mounted. Clarkson says turn the table 90° to the wheel. Easy enough, but the swing table has no stops. Do you guys just eyeball it, or do you use a clock to set that?
Since my universal head has no scale, I use the digital level in the phone to set the 7° primary angle. Clarkson then recommends using the "swan necked tool rest bracket". They show a pretty small diameter cup wheel. Mine is bigger. Size does matter. The swan neck hits the cup wheel.
I have metric bushes. They have 25mm OD's. Of the six straight shank cutter holders I have, only one has a 25mm bore (the rest 25.4 /1" ), but it is at the back. I tried stacking a bush into an longer stright shank holder, and then that into the short one which fits in the head. Had no way of locking the mill in length, so just pushed it in till it hit something. Was all a bit fiddly.
Setting the mill horizontal is another one of those simple concepts. Maybe the way I have my Clarkson close to a wall is the problem, but looking in from an angle I find it hard to judge the angle to get the support finger set right.
I think I need to make up a type F tool rest/finger from a thinner hacksaw blade. The one I have is too thick to allow it to spring out when turning from tooth to tooth. I have to back out o the spiral and then reinsert, which goes against Clarksons instructions.
Did the same for the 22° relief angle.
Result was ginding about 1mm off the end mill. The four flutes aren't very even. The center relief no longer existed, and it rubbed when I tried it, so I then relieved the center freehand on the end of the cup wheel. If I understand Clarkson correctly, the proper way to do this is to simply gash a cross with a cut off disk (Page 11 of the 1971 guide)
After grinding the rougher a bit, I had a go at butchering another beat up 10mm endmill. This time a center cutter.
Weird bit is, despite a pretty crap first attempt, both cutters cut much better than blunt.
Regards,
Mark
RotarySMP:
I made a lathe tool holder. I know that lathe tools aren't that critical, being single piont, and it is easy enough to off hand grind them. Still, this makes them look nice. I ground up two aluminium cutting bits, using 12° side rack and 35° top rack. If I'd offhand ground them, I would never have made such an extreme top rack, but they cut beautifully.
Mark
RotarySMP:
Since the first attempt at end mills was pretty crappy, I got a bit more serious.
My wheel dressing diamond is mounted on an 11mm shaft, for which I have no Clarkson bush, so I just clamped a vise to the table for dressing.
Then I made a new F style finger from a broken, thin hacksaw blade. For the set up this time I used just a straight shank holder and bush, and locked the end mill in with a set screw. The set up was much more repeatable, and I got a pretty nice even grind this time. In the end I used a handheld proxon grinder to hollow out the center.
T&C grinders are a lot of fun to play with. I can see the big advantage being the convenience. Since it only takes a minute to set up, you are more likely to touch up a tool, and use a sharp cutter, drill, etc rather than just getting by with a one which is a bit blunt.
Mark.
Fergus OMore:
At the risk of censure, criticism and probably worse might I say that I have a Mk1 Clarkson.
Whilst the instructions are correct, they were actually written for people in a tool room who were engaged in repeating the same old job- time after time on probably one setting! I doubt that few of us are doing much the same.
Frankly, people have been simplifying tool grinding for the home workshop which has little to do with 'factory methods' Model Engineer and Model Engineers Workshop have been full of variations which are based on putting a cylindrical cutter into in a square bit of steel block. It is fastened down with a grub screw after ensuring that one lip is aligned correctly. Quite simply, that is achieved by nothing more complicated that a piece of metal exactly half the thickness of the holding block. Once established, the whole block can be rotated 90, 180, 270 degrees with simple accuracy. How one fixes it to the Clarkson table is NOT using the proprietary on which holds a round insert. Probably an old fashioned nothing more than a couple of brackets would suffice. You can get a bit daft like me and fasten a Vertex BSO dividing head with appropriate collets onto the table but at a push, my original tooling was no more complicated than a bit of best B and Q 2" square wood and a few wingnuts, bolts and washers out of Wilkinson's
Going off at a sort of tangent, I had a look at this recent offering from Eccentric Engineering from OZ and their video of the Acute Tool Grinding rig. I even bought the book for ?£17 and whilst it doesn't tell the tides in HongKong Harbor which my Quorn probably does, it should fit onto the Clarkson table. Of course, it isn't the only simple and easily constructed method.
Me, and I have one extension piece for the spindle but I now want more to hold different abrasive disks. The trouble is that one needs 1/2"BSW Left hand taps and dies. Happily, a set came with my new to me Myford ML10 only days ago.
Does this all help and I hope that it will be regarded as advice. No doubt others will add their way. I'd also be please to read it
Norman
RotarySMP:
Does the table leadscrew on your Clarkson Mk1 also turn the wrong way? On mine, you rotate the handle clockwise to retract the slide. Both my Lathes advance the slide with clockwise motion.
Otherwise I really like the Clarkson. Today I needed to use a little 6mm HSS wood router bit which I'd ruined the cutting edges on last time it was used. Couple of minutes on the T&C and it is no longer 6mm, but cuts like a champ again.
A mate just bought a Hardinge in the UK (Lucky bugger), so I made a care package of tool bits ground for steel, brass and aluminium for him. I know it is overkill doing lathe tools on the Clarkson, but the resulting tools look really nice.
Mark
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