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Carbide insert Dovetail Milling Cutter

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Johan Crous23/12/2012 16:37:49
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35 forum posts
1 photos

Most of the suppliers are closed now that we are approaching the big days and I need a dovetail milling cutter soon.

I have given it some thought and think about making one with a carbide indexable tip. I am thinking of cutting an arbor and remove some metal of one side to place the tip. The tip is triangular with sharp points so a perfect 60 degrees can be done.

Any Ideas?

Stub Mandrel23/12/2012 17:18:13
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4306 forum posts
291 photos

I made one years ago from silver steel. I nver used it, instead found I was able to use a full size SS cutter instead.

Then a few months ago I needed to cut some small dovetails in steel, and it worked really well.

Vital to have a really good finish on the 60-degree blank before cutting the teeth.

Neil

Thor23/12/2012 19:51:55
1120 forum posts
31 photos

Hi Johan

If you want to make your own dovetail cutter with a carbide tip this site may give you some info. I made one a couple of years ago, it worked although I had to take fine cuts. It acts like a kind of flycutter.

Regards

Thor

Billy Mills23/12/2012 20:27:33
377 forum posts

Johan

Mike Cox has a 60 degree cutter on **LINK**

He has heaps of other good ideas too.

Happy Christmas.

Billy.

Michael Cox 124/12/2012 10:28:31
515 forum posts
27 photos

Johan,

Making a cutter is fairly straightforward and Billy has given a link to my site. The only thing to be careful of is to ensure that the cutting edge of the insert is exactly on the centre line of the cutter.

In use run at a moderate speed (eg 300 rpm for a 19 mm diameter cutter), keep it well lubricated and take shallow cuts especially as the cut advances into the metal. When you first start the cut, it is only the tip of the insert that is cutting andcuts of circa 0.4 mm are possible but when the cut is a nearly full depth then much small cuts should be taken.

I hope this helps

Mike

Johan Crous10/01/2013 15:37:45
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35 forum posts
1 photos

OK, I have done it. This was a trial and error job as it is my first milling job on my new mini mill. Previously I worked on my lathe alone.

 

I have used a bar of 25 mm dia. I have made use of a live centre to ensure it doesn't fly out of the chuck under speed.

 

I have cut a piece down to 16 mm as my stem and then I have used the abrasive cutt-off machine to shorten the piece.

 

I added the workpiece in the chuck and set the angle to cut at 30 degrees. In the background you can see an image of a previous job I worked on. Left, behind the chuck is my height setting jig (Magnetic).

 

Cutting Done.

 

Milling done on the previous attempt. I broke a twist drill when drilling the hole for the insert screw. The second drill driffted too far out, making the whole piece useless. Here you can see I used a bolt, but the second attempt I just used a straight piece of bar.

 

The insert is in. Perfect fit.

 

The available screw is too long.

 

A Dremel tool worked like a charm.

 

The end product. Similar dimentions than a 25 X 60 dovetail cutter. However a commercially available 25 X 60 mm cutter can cut dovetail 25 mm at its narrow measured point, 10 mm deep and of any length. This one however can cut up to 14 mm deep. Therfore bigger work is possible.

About 10% of the cost of a HSS cutter.

 

Now I am ready for Mr. Harold Hall's grinding rest and some serious additions to my limited number of QCTP holders.

Edited By Johan Crous on 10/01/2013 15:43:15

Stub Mandrel10/01/2013 19:35:41
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4306 forum posts
291 photos

That should become a short article in MEW.

Neil

JasonB10/01/2013 19:42:31
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Moderator
16279 forum posts
1722 photos
1 articles

Johan, do you have the bottom edge of the insert at 90deg to the tool axis? if so you may have problems with it rubbing the bottom of the cut.

I beleive the commercial ones have the bottom edge slightly raised towards the middle and compensate for the effect this has on the dovetail angle by also slanting the insert backwards.

J

Johan Crous10/01/2013 19:54:28
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35 forum posts
1 photos

Jason. No, it is slightly raised (very sligtly, just for the mentioned reason).

Neil, I have saved the pics, and a few more. I just don't know how to submit it for MEW, where to and the format required..

JasonB10/01/2013 19:59:32
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Moderator
16279 forum posts
1722 photos
1 articles

This gives gives details though a little out of date now.

**LINK**

Stub Mandrel10/01/2013 21:06:07
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4306 forum posts
291 photos

Johan,

If you send David Clarke a pm, I understand he will still be looking after MEW.

Neil

Ed Duffner10/01/2013 21:30:43
730 forum posts
61 photos

I might have a go at making one of these. Is the cutting face perpendicular to the cut or does the cutting edge lead or trail the apex of the insert? ...or does it depend on the type of insert?

Thanks,
Ed.

Thor11/01/2013 05:37:41
1120 forum posts
31 photos

Hi Johan,

your dovetail cutter looks great.

Regrads Thor

Ady111/01/2013 10:24:43
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3463 forum posts
513 photos

A small job which potentially makes a seriously useful tool

Great stuff

Johan Crous25/01/2013 16:47:28
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35 forum posts
1 photos

I have run it now while cutting a deep dovetail for a QCTP tool holder. It is working like a charm. The fluid coolant prevents it from heating up. The swarf produced is razor sharp splinters as the carbide tip is a very sharp, very positive raked tip. The finish is very smooth. It is just slow on my mini-mill, but I am getting there!

Stub Mandrel25/01/2013 20:36:36
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4306 forum posts
291 photos

That's the difference between turning and milling they never tell you about. Sawrf is a menace, but at least you don't keep getting splinters with a lathe!

Neil

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