So i need to make this part. It is .75 x .45 x .25

markknx

markknx

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I plan to Machinist from a piece of half by half Square stock making a few of them at the same time doing all machine work then cutting to size. The question is what would be a good way to machine the flat bottom V in the middle. Have not had a chance to measure the angles but was considering flattening the end of a countersink Machining the slot through the center Square and then gently over several passes cutting the inside angle.

I understand countersunk not really designed to cut sideways but was thinking for this later Cuts I may be able to get away with it. Trying to avoid repositioning the part multiple times or tilting ahead of the mill.

The part is part of the clamping mechanism to hold a scope to a pellet rifle.20180328_050105.jpg
 
Little pieces can be difficult to hold. I would machine multiple pieces on a sing;le bar, cutting apart and facing as a final operation. I would use an angle vise and an end mill. It looks like your angles are 45º so you could face cut one side and side cut another, making all three cuts in the same setup. The floor of the vee would be cut in a separate setup. The difficult part would be matching the surfaces for a clean intersection.

A countersink isn't a particulaly good choice for what you are trying to do. Countersinks are not meant for unbalanced loads. You can buy chamfer mills or drill mills that are intended for that type of operation.
 
Bill Gruby said:
You could almost make those with just a file.

"Billy G"
Click to expand...

I remember when I went thru the Army Machinist course at Aberdeen Proving Grounds the 1st project was to make a 4" anvil with nothing but a hacksaw and a file. Bill's right. In the amount of time you've thought about this project and posted you could have had at least 2 done.
 
What kind of material? Are the angles just for clearance? Yes, a counter sink will work. I have done the same thing, no problem. When you grind the bottom of the countersink, don’t do it flat. Do it on an angle, so the bottom cuts. Maybe run a regular end mill through the area to remove most of the material so the countersink does not have to work as hard…Dave

I was talking about a single lip countersink
 
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You could have been a Tool & Die Maker ALL your life. And you thought you knew all there was about machining material, the metrology of it, metallurgy and so on. Then you were asked to do some micro machining??? It’s basically another world with the basics as similar. My point is, you can do it. Just think your steps through FIRST. Don’t remove material that could be used later for measuring, holding, etc. until you are ready. Leave the stock long. Makes for a handle and or you can find it when falls to the floor. That’s enough, good luck…Dave
 
For a one-off part like this... Hold the roughly formed part in a machinist vise and use a couple small hand files to finish the details.

Ray
 
If the angles are standard, then you can use a V-cutter to cut them. V-cutter router bits are available in several different angles.

Here is a V-cutter that I use for various projects, this is a 90° fiberglass drill that I picked up somewhere. But I also use carbide tipped wood router bits for metal machining.
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Making a Weldon shank on a tool holder
1522251562397.png

For non-standard angles this little trick works pretty good if you have a tool maker vice. Or if not, make a fixture for the part and you can do the same thing.
1522251884805.png
 
Jim what is that gadget with the red pointer called? I want one
Mark
 
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