Recommendation on t-slot cutter? And a finally functional CNC mill..

Recommendation on t-slot cutter? And a finally functional CNC mill..

Joined: September 27th, 2015, 4:22 pm

April 11th, 2018, 1:21 am #1

Anybody have a good recommendation on a t-slot cutter type or good source for them? I want to cut some t-slots for ASAs in frames, as well as be able to do the undercut lip on Empire and PE style feedneck bosses. Most of the cutters I can find seem to be targeted at rather large slots, nothing in the 3/32" neighborhood (t-slot for a Relay is .115" tall ideally, so there or smaller).

On a related note, I finally got a small amount of chips made on my CNC mill, and it runs oh so much better than my converted mini mill ever did.  Bit of a SNAFU zeroing the first test part (not this test piece, a toe clamp in 4140) due to me not fully understanding the touch off procedure in LinuxCNC vs Mach 3, but lessons learned.  And it proved that my enclosure is effective at protecting me from exploding carbide, so I'll call that a win.

Drew up a quick little test piece in Fusion to test how well it would do circular interpolation and angles, as well as to double check dimensions. 










Features all came out about .002" - .003" oversized.  Need to dial in whatever caused that, but very happy with how it came out and how smoothly it ran.  The circular boss is a very consistent diameter, and the angled feature has pretty much the exact same surface finish as the rectangular part.

Thanks
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Joined: January 1st, 1970, 12:00 am

April 11th, 2018, 9:34 am #2

Noice!

Just out of curiosity, why'd you pick that machine? Or, I suppose, by what mechanism did you wind up with that particular machine, if it wasn't in fact a specific choice? 😁

As for the T-slot cutters, it's been a very long time since I ordered any, and the vendor from whom I used to buy them was bought out or closed down probably ten years ago. Looking around at current vendors... yeah, virtually nothing under 1/2". Hum.

Theoretically- and in an emergency- you could use Woodruff cutters, but they're not properly designed for T-slotting. Not sure there'd be much of a wider selection there, either.

I'd be curious to know of a good vendor myself.

Doc.
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Joined: November 17th, 2014, 11:09 am

April 11th, 2018, 12:12 pm #3

0.003"?

Did you verify the diameter of the bit?
(Cut a straight groove, single pass) and measure the width of it.
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Joined: November 30th, 2014, 1:36 am

April 11th, 2018, 2:26 pm #4

y0da900 wrote: Anybody have a good recommendation on a t-slot cutter type or good source for them? I want to cut some t-slots for ASAs in frames, as well as be able to do the undercut lip on Empire and PE style feedneck bosses. Most of the cutters I can find seem to be targeted at rather large slots, nothing in the 3/32" neighborhood (t-slot for a Relay is .115" tall ideally, so there or smaller).
You might give AB Tools a call, they can do a custom carbide tool ib the form that you seem to be looking for.  abtoolsinc.com
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Joined: October 28th, 2014, 1:06 am

April 11th, 2018, 4:46 pm #5

Looks nice.  

As far as a t-slot cutter goes, do you have a lathe?  Can you take an end mill with the correct diameter and grind the shank down?  I'm about to try that to make some custom barb fittings.
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Joined: September 27th, 2015, 4:22 pm

April 12th, 2018, 2:04 am #6

DocsMachine wrote: Noice!

Just out of curiosity, why'd you pick that machine? Or, I suppose, by what mechanism did you wind up with that particular machine, if it wasn't in fact a specific choice? 😁

Doc.
Mostly through dumb luck and timing.  I was browsing the CNC machinery on ebay shortly after getting a bonus at work, and stumbled upon this for $3500, including the mill stand, control system, and a 4" vise.  Looking at equivalent setups in either a PCNC440 or 770 was well over twice the price as were Pulsar options from Novakon, so I jumped on it knowing I would need to do some tweaking to get it quite where I wanted it as well as repair my garage around it to help protect the investment.  While, in the long run, I think I would have preferred a Tormach (either one), at the point I greatly preferred the cost difference and plan on making good use of it.

Snowtroll wrote: 0.003"?

Did you verify the diameter of the bit?
(Cut a straight groove, single pass) and measure the width of it.
I have not verified that yet, I made the classic assumption that a brand new tool came as advertised - I highly suspect at this point that you are spot on with the diameter being off.  I went through the g-code and it was instructed to follow the correct path for a .250" diameter tool.


y0da900 wrote:You might give AB Tools a call, they can do a custom carbide tool ib the form that you seem to be looking for.  abtoolsinc.com
I had forgotten about them, but looking at the base offerings I would be looking at $100+ for a single tool.  Might end up having to go this route in the future, but I would want to plan on doing more than a very intermittent feedneck or frame t-slotting to justify that.

jr9999 wrote: Looks nice.  

As far as a t-slot cutter goes, do you have a lathe?  Can you take an end mill with the correct diameter and grind the shank down?  I'm about to try that to make some custom barb fittings.
I do have a lathe, but am not equipped to grind an endmill on it, though that would be an interesting thing to try should I ever get set up for that.





I got directed to an ebay auction on MCB, as well as pointed toward some McMaster parts that looks promising (not sure how I missed that the first search) :

https://www.mcmaster.com/#3031A13
https://www.mcmaster.com/#8765a39/=1cdgkch
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Joined: November 23rd, 2014, 9:43 pm

April 12th, 2018, 3:12 am #7

Harvey Tools and Internal Tools make the tools you need. Not a big fan of internal but they’re cheaper than Harvey.

I’d take a look at runout on the tool, dial near the tool holder and near the tip and see if the reading is the same.

Also, 2 (and maybe 3) flute endmills are toleranced differently than 4 flutes. Slot drills will be +0 -.002.
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