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Making a Cutter Holding Block

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Bernd:
John,

So there is hope for me after all?  :ddb:

Alright. :clap:

Bernd

bogstandard:
Almost  :lol:

Bernd:
Ok, we're getting closer to actually cutting flutes. I finally have the cutter block finished and the adapter plug that will allow me to hold a cutter with a 1/2" (12.7mm) shank. Plus I've also made the cutter blank.
Hopefully I'll be able to cut the flutes in the blank on Saturday.

This first picture shows all the parts. On the right is the cutter block with three 5/16-18 holes for set screws (grub screws), the cutter bushing which will take the dia. of 1.125" (28.5mm) down to the 1/2" (12.7mm) dia. It also has the holes in it. They 1/4-20. On the right is the cutter blank. It will have three flutes cut into it. The reason I didn't put the screws in the bushing is that they are a bit long. I need to trim them a couple of thou so they will be below the O.D. of the bushing to be able to fit in the bore of the holder.



Here's a close up of the bushing. Notice I've mill a flat down the center. This will help with the burrs that get rasied on the bushing from the set screws that hold it in the cutter block.



Here the cutter blank is inserted in the bushing.



And here it is all assembled ready to be put in the mill vice. And yes I will rememebr to put the screws in to hold the cutter blank.



I'm hoping to have the cutter made tomorrow. I'll post more pics when I'm done.

And I'm starting to get a serious case of  :proj:  :ddb:  :ddb:


Bernd

Bernd:
Last installment of making a cutter block and the making of a three fluted cutter.

Here I'm setting up the depth on the Z axis. I use a piece of paper to tell me when I'm close to touching the part. Then I'll need to go down half the dia. of the part I'm setting the cutter to. I also need to do this on the Y axis. Same procdure. Touch the side and go in half the dia.



I took several cuts until I just touched the pilot OD. Here's the first flute.



And here's what it looks like after a trip around the cutter block. Each index is 120 degrees.

 

After indexing the cutter block 120 degrees 3 times I've got the three flutes roughed out. Next I need to thin down the side edges to about .075" (1.9mm). No set dimension on this. Just make it in proportion to the cutter size. I'm using a height gage to scribe the line that I'm going to mill up to get that .075" (1.9mm) top land.

I'm also going to rotate the cutter blank and bushing a few degrees clockwise to remove the material I need to get to that line.



Here you can see clearly that I have narrowed down the flutes to that scribed line. It takes several trips around the cutter block to get to this step. That is the last flute being cut.



The bushing has some raised material from clamping down with the set screws. So milling that flat spot on the bushing was useless in this situation. The cutter is on the right. More work needs to be done on the cutter so it will cut.



After painting on some layout dye I use a file to file away some material for clearance. You can see the scribe line on one of the flutes. This helps to see how far you've filed.



Notice the tap that is broke off in the hole? Yup, I screwed up. I was going to put a brass pilot in because the one that was turned on the blank was pretty well beat up from milling and filing. So I thought I'd use a 5-40 thread. I even hand tapped it but was a bit to enthusiastic and broke the tap. But since I was only going to use this cutter once I figured it will work without a pilot.

What I've done is coat the cutting surfaces with layout dye again and filing the relief angle on the cutter. You'll want about .010" (.25mm) top land.



I didn't bother to heat treat the cutter since it's going to be a one time use and it will be cutting aluminum. But if I had to drill into a ferrous material I would have heat treated the cutter. I guess I forgot to mention that tool steel was used in the making of this cutter, either water hardening or oil hardening was used. I can't remember what I bought. It's been many years since I purchased the steel.



Well this proves that it cuts. There are chips and it looks like a hole is started. Lets see if it'll make it all the way through.



Yup, made it all the way through.



I've covered a lot of ground here. What I have shown can be used for other things besides making cutters. Although this method of indexing is not precise it will work for something like this. It's useful for putting hex heads on bolts or drilling holes at 60 degree intervals.
The reason I say it's not precise is that the hex stock is not made to very close tolerances and the hole that you drill through the center also needs to be dead center to all the sides. When I checked the bore on this block I found I was off center by .008" (.2mm). One reason is that my chuck in the lathe was off .003" (.07mm). Not good for precision work but good enough for cutter making.

Now back to making the clamp plate for the index head.

Bernd

bogstandard:
Bernd,

Concept proven, cutter made and the job done. :clap:

Nothing else to be said, other than very well done, and very instructive. Even I could make one now.


John

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