Shortening a CNC router bit

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redwood
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Shortening a CNC router bit

Post by redwood »

OK, so I bought a extra long 1/4" endmil. I guess that I didn't pay attention to the overall length, only the cutting length. Well I need to cut the shank down, so that the bit will fit over my piece of wood.. I'm sure it's hardened steel as my jigsaw with a brand new thick metal blade would not even scratch it. Any Ideas?
Mark
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gkas
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Re: Shortening a CNC router bit

Post by gkas »

redwood wrote:
Fri Sep 03, 2021 12:38 am
OK, so I bought a extra long 1/4" endmil. I guess that I didn't pay attention to the overall length, only the cutting length. Well I need to cut the shank down, so that the bit will fit over my piece of wood.. I'm sure it's hardened steel as my jigsaw with a brand new thick metal blade would not even scratch it. Any Ideas?
Buy another bit. Any attempt to cut will ruin the heat treat.

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SteveNelson46
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Re: Shortening a CNC router bit

Post by SteveNelson46 »

They're probably carbide steel or even solid carbide. The only sure way to cut them would be to use a metal lathe with a diamond tipped cutter. Even then, as GKas said, you will probably ruin the heat tempering and hardness.
Steve

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Leo
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Re: Shortening a CNC router bit

Post by Leo »

You are not going to ruin heat treating on Carbide tool by cutting the shank.

Tungsten Carbide is a powdered metal product which is compacted into a form compressed under extreme pressure and sintered at somewhere around 2000 degrees. It is a finished product. To my knowledge it is not heat treated in a convention sense like HSS is heat treated. Carbide is not steel in a conventional sense like HSS. It is an entirely different grain structure than steel like HSS. Carbide inserts are made from powdered tungsten in a mold and sintered. Carbide rods are made from powdered tungsten and sintered then ground into various tools like router bits, end mills, drills etc. There is a LOT more to the story.

You WILL destroy anything that you try to cut it with.

If you have a CUT OFF abrasive saw you can cut it.
You "might" be able to cut it with a angle head grinder.

BUT - ONLY with a diamond wheel. Even at that, it will be VERY difficult to do.

I would recommend that you buy a new cutter.

Perhaps you can sell the long length cutter.

Even if you sell it at a lower price than you paid for it - you loose less money than leaving it in the drawer of destroying it by trying to cut it.

If you tell me what the cutter is - I may be interested in buying it, but I will not be willing to pay more than a new cutter with shipping included.
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jimandi5000
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Re: Shortening a CNC router bit

Post by jimandi5000 »

redwood wrote:
Fri Sep 03, 2021 12:38 am
OK, so I bought a extra long 1/4" endmil. I guess that I didn't pay attention to the overall length, only the cutting length. Well I need to cut the shank down, so that the bit will fit over my piece of wood.. I'm sure it's hardened steel as my jigsaw with a brand new thick metal blade would not even scratch it. Any Ideas?
I am not sure what you paid for it. But if you have friends with CNC's I would do some horse trading if not, just order the correct bit. I would not try to cut off the bit.
Thanks,
Jim

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SteveNelson46
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Re: Shortening a CNC router bit

Post by SteveNelson46 »

I wonder what is used to sharpen or shape a router bit that is solid carbide? My guess is that it would have to be something harder that the carbide itself. Diamond or maybe CBN (cubic boron nitride)?
Steve

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Re: Shortening a CNC router bit

Post by Rcnewcomb »

- Randall Newcomb
10 fingers in, 10 fingers out, another good day in the shop

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Re: Shortening a CNC router bit

Post by martin54 »

As others have said best to just buy the correct bit, the other problem you may have with shortening the shark is that the shank then won't be long enough to sit in the collet correctly :lol: :lol: :lol:

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Re: Shortening a CNC router bit

Post by redwood »

Here is the bit I purchased. 777-2256: 777-2256 1/4" Carbide Square End Mill Extra Extra Long 2 Flute AlTiN

Purchased from the Carbide Endmill store Price was $ 37.38 + shipping, which was outrageous in my mind $20 and took 11 days to receive.

3" cutting length, 6" total length. In my case, the shank could be 1" shorter.

I checked their site and they don't have what I need. Their lengths go from 4" to 6". 4" is too short and 6" is too long. For the use I was looking for, I could probably get away with 5.5" long shank, though 5" would give me some wiggle room. I wanted it to rough finish a oak bowl that is in a sort of figure 8 or kidney shape.
Mark
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Re: Shortening a CNC router bit

Post by Leo »

Randall - nice video

When I was working at Winchester back in the early 90's we were considering buying a Walters CNC Cutter grinder to make and sharpen end mills. At the time Winchester was spending about $750,000 a year in tooling. That was ALL tooling not just end mills. We watched as Walters took a 3/4 diameter blank of solid carbide and make a center cutting 4 flute 3/4 diameter end mill in 15 minutes. The machine was $300,000. I also went to Huffman in South Carolina to look at their cutter grinders. I don't know how many people have ever ground carbide or see it being done, but 15 minutes was mind blowing. I am sure in 2021 the technologies are far more advanced.
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Leo
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Re: Shortening a CNC router bit

Post by Leo »

redwood wrote:
Fri Sep 03, 2021 8:41 pm
Here is the bit I purchased. 777-2256: 777-2256 1/4" Carbide Square End Mill Extra Extra Long 2 Flute AlTiN

Purchased from the Carbide Endmill store Price was $ 37.38 + shipping, which was outrageous in my mind $20 and took 11 days to receive.

3" cutting length, 6" total length. In my case, the shank could be 1" shorter.

I checked their site and they don't have what I need. Their lengths go from 4" to 6". 4" is too short and 6" is too long. For the use I was looking for, I could probably get away with 5.5" long shank, though 5" would give me some wiggle room. I wanted it to rough finish a oak bowl that is in a sort of figure 8 or kidney shape.
Mark,

First off - you do not need TiAln coating.
Generally I use uncoated end mills.
Coatings can blunt the cutting edge a little and TiAln is a pretty thick multilayer coating.

I use carbidedepot.com a lot of the time.

The length of 5" of 5.5 " is non standard. I don't see that on any vendors list.

Can I ask -- what is your limitation in using that tool? Is your machine limited in "Z" axis movement? Can you mount the material differently? Can you move your spindle higher in it's clamp, Can you remove the spoilboard?

You "might" be able to bring it to a local machine shop to have the end cut off. They can do is on a surface grinder with a diamond cut off wheel. CBN will not cut carbide.

I would be willing to buy that cutter from you for $35.00 including shipping. I would walk away from $20 for shipping. You can ship in a bubble envelope as long as the end mill is in the plastic tube it should have shipped in.
Imagine the Possibilities of a Creative mind, combined with the functionality of CNC

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Re: Shortening a CNC router bit

Post by Wayne Locke »

A sharpening shop which does.router bits can do it.

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Re: Shortening a CNC router bit

Post by Leo »

agreed
Imagine the Possibilities of a Creative mind, combined with the functionality of CNC

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