How would you make this cutter?

[Chewy]

I want to make a small wooden endpin puller for a violin or viola. It is very simple or was until I started improving it. You can buy a Chinese knock-off on Ebay for ten dollars. But why do that when I can spend a week making it. . Also the dimensions given don't fit the problem instrument that started this. The hole diameter is shown as 8mm but this viola needs 9mm. The picture shows the finished piece. The hidden lines are for a 1/2x 20 screw (not shown) that tightens down on the head of the endpin. The Chinese item has a flat ledge to go under the head. When I checked a handful of replacement pins, they have an angle of around 150 degrees taper. In use, slide this puller under the head of the pin, tighten the clamp bolt and then twist and pull till it comes out.
I have several ways to do this. Drill the holes and us a Tee slot cutter to make the clearance area. Then make a 150 degree dovetail cutter and pull up-words to get the angle. Make a single cutter combining both. Enlarge the clamping bolt to 3/4". Drill the 9 mm hole and and 11/16" tapping size hole. Make a 150 degree d bit and "countersink" the ledge.
I have never made a dovetail or endmill style cutter. This is small enough to make them until I get it right. The cutting edge has to be dead on the center line. Is a 90 degree edge sharp enough to do a good job on 6061? Should I angle the edge slightly using a ball endmill? I plan on hand filing some relief on the back side so it doesn't rub. The shaded area on the cutter is where the cutting edge is. One flute enough or do I need to do more?


Thanks in advance

 

[davidpbest]

Curious how you get this onto the tuning pin in the first place.

 

[Chewy]

It is a U shaped puller that slides into a groove on the pin. Think of using two fingers to hold a round head machine screw and then pressing down on the top of the head with your thumb to trap it. I pulled maybe 50 of these out with my fingers and then hit one that was really stuck. If this was a machine screw, you would lock down with a pair of vise grips and then turn. Throw it away and put a new screw. Problem is that these are all hand fitted and this one was larger then my biggest ones in stock. Had to call a supplier and he measured a bunch to find one a little bigger that I could hand fit. Worse come to worst. I could make one on the metal lathe as ebony is usually worked with machine tools. But it would cost a whole lot more then the $1.50 to buy one. Plus the time would be maybe an hour vs 1-2 minutes.

 

[davidpbest]

Oh - from your drawing I thought it was a solid cylinder with a hole in it shaped like this. And I was wondering how you were going to get it over. the pin.

 

[Eddyde]

I'd start with a small slotting mill or router bit and regrind it to get the angle on the top.
Maybe something like this:

Heavy Duty 5/16" HSS T-Slot Milling Cutter NEW !} | eBay

Cutter Thick: 17/64". Cutter Dia. A vertical slot must be cut first, so that the neck and shank can enter the cut. You may ask for freight cost before buying tools. Product features. Overall Length: 2-11/16".

www.ebay.com

 

[Chewy]

Have any of you used a cutter like this to cut T-Slots? Have several here from Ebay assortments. Sorry about the lousy photos.

 

[Eddyde]

That would work too!