# Tee Slot Cutting



## Mchauck01 (May 26, 2020)

I need to cut two Tee slots in a 1 1/4” thick piece of A36 hot rolled steel. I have never done this. I have the first cut made 1/2” wide by 1” deep. Now I need to cut the bottom T. I have a 1/4” x 7/8” cutter and a 3/16” x 1” cutter. I would like the finished dimension of the bottom cut to be 3/8” x 1”. What RPM? Should I just use the 1” cutter or start with the 7/8”?


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## BtoVin83 (May 26, 2020)

RPM= SFPM/((Dia*Pi)/12)
SFPM = ~75
Feed t=rate = .002 per tooth
Watch the chips most tee slot cutter breakage occurs because the chips can't get out of the way


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## RJSakowski (May 26, 2020)

Am I seeing this correctly? A left and right hand cutter?


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## BtoVin83 (May 26, 2020)

No just left hand but the cutters turn different directions


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## BtoVin83 (May 26, 2020)

I don't ever remember seeing  counter rotating cutters before.


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## Mchauck01 (May 26, 2020)

BtoVin83 said:


> RPM= SFPM/((Dia*Pi)/12)
> SFPM = ~75
> Feed t=rate = .002 per tooth
> Watch the chips most tee slot cutter breakage occurs because the chips can't get out of the way


Wow thanks. So if I got this right, 
RPM= 75/(1”*Pi)/12 for the 1” cutter?  And yes. One right. One left. I will of course run reverse for the LH.


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## Mchauck01 (May 26, 2020)

BtoVin83 said:


> No just left hand but the cutters turn different directions


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## Mchauck01 (May 26, 2020)




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## derf (May 26, 2020)

Those will work, but you'd be better off with a T slot cutter, they have staggered teeth.


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## benmychree (May 26, 2020)

derf said:


> Those will work, but you'd be better off with a T slot cutter, they have staggered teeth.


Just what I was going to say, buy a T slot cutter, it will cut much more freely that the woodruff keyseat cutters that you have.


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## Aukai (May 26, 2020)

I bought a 30 dollar lot, and was wondering what this was, it fits the description, made in Poland,,,,T slot cutter?


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## benmychree (May 26, 2020)

Yes, T slot cutter


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## Mchauck01 (May 26, 2020)

derf said:


> Those will work, but you'd be better off with a T slot cutter, they have staggered teeth.




Yup. You are right. I got it done. But I had to sharpen my cutter midway. I’m gonna buy a t slot cutter like you said. I guess I need a new woodruff cutter too!!


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## GunsOfNavarone (May 26, 2020)

I'm glad this thread is here... So in T slot cutting, tou would mill the top opening, come back and using a t-slot cutter, cut one side the the other? How about dove tail cutting?


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## Mchauck01 (May 26, 2020)

GunsOfNavarone said:


> I'm glad this thread is here... So in T slot cutting, tou would mill the top opening, come back and using a t-slot cutter, cut one side the the other? How about dove tail cutting?



I cut the center slot full depth. Then I cut the bottom tee full width


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## ttabbal (May 26, 2020)

With dovetails, I cut the center a couple of thou deep. So the dovetail cutter isn't trying to cut the slot as well.


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## GunsOfNavarone (May 27, 2020)

ttabbal said:


> With dovetails, I cut the center a couple of thou deep. So the dovetail cutter isn't trying to cut the slot as well.



Just a question, why would you not want to cut the center full depth and cut the angles secondary? Maybe if you had a less massive/powerful mill? Then would it make more sense? I have not yet cut T or Dove tail slots though it has been on my need/want list for a couple years, just don't know how to approach it.


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## ttabbal (May 28, 2020)

It's mostly that the cutters at the edges can be a bit fragile. I don't think it's big issue with the insert style cutter I was using, but it was mentioned by a few people that it was recommended. And the commercial AXA holders I have were made that way. It didn't seem like something you would do in a commercial product if there wasn't a good reason.


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## ttabbal (May 28, 2020)

It's mostly that the cutters at the edges can be a bit fragile. I don't think it's big issue with the insert style cutter I was using, but it was mentioned by a few people that it was recommended. And the commercial AXA holders I have were made that way. It didn't seem like something you would do in a commercial product if there wasn't a good reason.


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## theperfessor (May 28, 2020)

Run dovetail and T-slot cutters in set screw type holders. Don't depend on friction/collet holders for any but the smallest cutters. If your cutter has a Weldon/flat shank it's for a reason!


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## GunsOfNavarone (May 28, 2020)

Thanks @theperfessor I no doubt would have tried an R8 collet which now that I think about it...makes good sense that it would be prone to slip. I can't wrap my head around the idea of one pass cutting a t or dove slot. Thinking about the height/width DOC...I would never attempt that, but everyone here seems to say that is the way to do it. 
Hope I didn't take this thread off topic, did a search and this seemed along the same topic.


theperfessor said:


> Run dovetail and T-slot cutters in set screw type holders. Don't depend on friction/collet holders for any but the smallest cutters. If your cutter has a Weldon/flat shank it's for a reason!


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## ttabbal (May 28, 2020)

I did use a collet, my cutter doesn't have a flat. I also did not do the dovetails in a single pass. I did about 0.040 on each side at a time. Then measured when I was getting close. I actually overshot a little bit, but not enough to cause a problem.


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