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Stop ended Tee slot in Meehanite

Bad idea??

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Chris V17/04/2021 11:38:29
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310 forum posts
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I have a GHT pillar drill, the base has a tee nut fitting specifically to fit to my Myford M Type cross slide, ie it does not have the usual base casting. Whilst it is not in use I wish to have it stood upright so thought I'd make a base that the tee nut can fix into. I see Noggin End do Meehanite by the inch by 120mm or 150mm dia which would suit my needs, I think.

My plan would be to use my Amolco to cut the tee slot part way through, stop and back out, having roughed out the centre part with a straight cutter. The tee slot is 3/4" at its widest.

Ive never cut a tee slot, or yet milled cast iron or Meehanite for that matter.

My question is if I got the slot cut with the tee cutter, should I stop the mill and back the cutter out the slot, or keep it running and back out, running the risk of climb milling?

I'd really rather not mess either the metal or cutter up first time I try!

Chris.

John Haine17/04/2021 11:54:18
3826 forum posts
222 photos

I suspect the Amolco (if it's like the one I used to have) might struggle with a 3/4 tee slot cutter TBH. Why not just have a tapped hole in the (heavy) base that the tee bolt fits, take the nut off first (putting it somewhere safe of course...).

Andrew Johnston17/04/2021 12:03:23
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6009 forum posts
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Keep the cutter running otherwise you run the risk of damaging the edges. When making the cut, on one side of the cutter a tooth is conventional milling, as the tooth moves round to the other side it is climb milling. When you reverse the feed direction all that happens is that the conventional and climb milling sides swap over.

Continuously extruded cast iron machines beautifully, if a little messy.

Andrew

not done it yet17/04/2021 12:47:35
5853 forum posts
20 photos

A couple of pieces of rebated steel strip, screwed to piece of suitably sized flat bar would suffice? No need for any precision and a good ‘lead-in’ might be advantageous?

I like the KISS principle.🙂

Dave Halford17/04/2021 12:48:01
1439 forum posts
12 photos

If the mill chokes a shop vac will help with dust removal.

it will definitely choke if the slot is blind.

Chris V17/04/2021 12:48:53
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310 forum posts
42 photos

Hi John,
Thank you for that. My first thought was a pin in a base as you suggest, certainly easier and little chance of me messing it up.
But yes I'm concerned I might mislay the tee nut & bolt and the challenge of trying to do what I actually want to is still there....Yes I am concerned about how the Amolco will cope though....hmmmm

Thank you Andrew, ah ok great well at least its not a non starter then, I guess the only way I'm going to find out if the Amolco can cope is to try it, it will only be about 3" long cut (-:

I would hope to turn a moulding around to rim, would I be better cutting the slot first, if after it would be an interrupted cut?

Chris.

Andrew Johnston17/04/2021 13:09:29
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6009 forum posts
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As you no doubt know the centre slot is cut a bit deeper than the T-slot, so that the T-slot cutter only cuts on the periphery, not the middle.

Andrew

Hopper17/04/2021 13:31:50
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Posted by John Haine on 17/04/2021 11:54:18:

I suspect the Amolco (if it's like the one I used to have) might struggle with a 3/4 tee slot cutter TBH.

The M-Type T slot is only 9/16" (.562) wide so should not be a problem.

If its done as Andrew suggests with the centre slot milled a few thou deeper than required, the T cutter is only working on the two edge areas. The central slot is., from memory, about 3/8" wide so a cutter with a good sized shank can be used.  The M-type's T slots are a bit larger than the later ML7s but not much.

 

 

 

Edited By Hopper on 17/04/2021 13:37:22

Chris V17/04/2021 14:06:26
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310 forum posts
42 photos

Thank you. Yes I read about cutting the centre slot a tad deeper than the tee last night on another thread, good tip.
I can them take a final deeper cut to give a flat bottom.

Out of interest I just triple checked, (mines a Myford M type), all three tee slots vary very slightly but the rear one I made the tee nut for is 17mm or 11/16" at its widest, my tee nut is a touch under this for clearance. Then looked at ARC E. and see they have an 18mm wide tee cutter.

Looking at M machine they have EN1A or EN3 steel available in suitable sizes, would either of these be easier to mill the slots in, or harder?

Chris.

Emgee17/04/2021 15:27:16
2010 forum posts
253 photos

Chrisv

I believe the cast iron will be easier to cut than the other materials listed, best if you have a vac running to keep the chips clear from the slot to reduce the chance of jamming.

Emgee

Chris V17/04/2021 16:47:24
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310 forum posts
42 photos

Thanks very much Emgee!

Chris.

John Pace17/04/2021 18:11:14
254 forum posts
170 photos


Hi
The tee slot cut in this table is 250 grade cast iron it cuts very easily ,you
need to clamp the job down really well and lock all the unused axis ,when i
cut these i always leave about a 1/16 of an inch at the bottom of the slot
for the cutter to work against it takes a lot of the shock of the interrupted cut
away ,the cutter here is from Arc Euro 16mm dia 7mm deep ,obviously the
start needs to be at full depth.If you can the sharp edges of the cutter should be
chamfered to avoid a sharp corner in cast iron, about 1/2 mm is enough.
Power feed and a vacuum cleaner if you have it.

Johnblind tee slot on 250 grade cast iron.jpg

Chris V17/04/2021 18:21:50
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310 forum posts
42 photos

Thank you John, that's encouraging to hear. I'm glad my first tee slot isnt at an angle like yours!

A Mars Bar before winding the handle will have to do for me! (-:

I understand you put paper between the mill bed and lump you are milling to help stop slippage, do you also use paper between clamps and the job ie on the top face?

Chris.

John Pace18/04/2021 10:11:44
254 forum posts
170 photos

Posted by Chris V 17/04/2021 18:21:50
I understand you put paper between the mill bed and lump you are milling to help stop slippage, do you also use paper between clamps and the job ie on the top face?

Chris.

You can do this if you wish ,i use these plate pieces to surround a job
clamped to the mill table ,they are nothing special just rough cut, mill clamping.jpg used with the normal clamping methods will hold a job securely in
place.
The part in the previous photo had bolt holes on the underside to fix to
the pair of angle plates.As this part was eventually ground on all four sides
it needed to be made and held in this way.

John

Edited By John Pace on 18/04/2021 10:13:54

Chris V18/04/2021 11:10:58
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310 forum posts
42 photos

Thank you John, I was thinking of using 4 x anti slip stops, don't recall seeing corner pieces like yours before except for woodworking...seems like a great idea!

Do you consider the x4 you show an ideal set, ie with x2 straight slots & x2 at 45*?

Would you still use paper between, or not necessary?

Chris.

John Pace19/04/2021 09:17:31
254 forum posts
170 photos

Hi Chris

Just make them to suit what you are doing ,paper in between the work and the table can be useful to protect an already finished surface.

John

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