endmills/slot drills

This forum is dedicated to those hobbyists with the 3-in-1 metalworking machines. Mill-Drill-Lathes. Tips, techniques, modification and use of these machines is topical.

Moderator: Harold_V

Post Reply
johnnyone
Posts: 4
Joined: Tue Nov 27, 2012 2:42 pm

endmills/slot drills

Post by johnnyone »

hi
i've got a clarke cl500m 3 in 1 lathe mill with a mt3 style colett type on the quill. whats the bigget end mill i can fit into it? my supplier tells me its a 12mm endmill. can i go upto 16mm on this mill?
SteveM
Posts: 7763
Joined: Mon Jun 27, 2005 6:18 pm
Location: Wisconsin

Re: endmills/slot drills

Post by SteveM »

I've never seen metric MT3 collets, but in inch size they go up to 3/4".

Steve
Torch
Posts: 1684
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: endmills/slot drills

Post by Torch »

SteveM wrote:I've never seen metric MT3 collets, but in inch size they go up to 3/4".
... which is very close to 19mm.

It's really more of a question about can your machine handle it rather than if it will fit. Bigger mills need more power and greater rigidity. Obviously, how tough or soft the material being milled is will also be a factor. Aluminium is a lot more forgiving than steel.

Also, be aware that any tram error will be more pronounced with a larger endmill.
johnnyone
Posts: 4
Joined: Tue Nov 27, 2012 2:42 pm

Re: endmills/slot drills

Post by johnnyone »

thanks for that. i'm looking to cut a 16mm slot in 12mm mild steel
Torch
Posts: 1684
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: endmills/slot drills

Post by Torch »

To be honest, I think you would be better off to cut a narrower slot -- maybe 15mm, almost to depth, then widen it on each side. Depending on the depth, you might need to take several passes to do that too. Bring it to 0.01 or 0.02mm shy of the final dimension. If the dimension is really critical, let the part cool before making the final two passes to finish depth.

Make sure your column is clamped very tight and don't try to take big bites when slotting. The tool bit will want to torque the mill and can rotate the column if the motor power combined with reaction force can overcome the clamping force. Don't Ask Me How I Know This (tm). I would limit the depth of cut to 1mm or less per pass in steel.
johnnyone
Posts: 4
Joined: Tue Nov 27, 2012 2:42 pm

Re: endmills/slot drills

Post by johnnyone »

thanks for that. i did'nt say earlier, but this will be a 16mm radius slot through 12mm mild steel.+45 deg to -45 deg on a rotary table.
User avatar
GlennW
Posts: 7284
Joined: Sun Apr 15, 2007 9:23 am
Location: Florida

Re: endmills/slot drills

Post by GlennW »

Bore a 16mm hole at the termination points of the slot, and then mill the arc making two much narrower slots to join the bores using a small end mill.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!
johnnyone
Posts: 4
Joined: Tue Nov 27, 2012 2:42 pm

Re: endmills/slot drills

Post by johnnyone »

the main problem that i've got with the cl500m is that i can't seem to get the mill head to stay put.

slotting out a hole, the damm thing either jumps to the side or wanders off line.

its not the job thats moving, its the mill head! any advice would be welcome.
User avatar
warmstrong1955
Posts: 3568
Joined: Thu Mar 18, 2010 2:05 pm
Location: Northern Nevada

Re: endmills/slot drills

Post by warmstrong1955 »

johnnyone wrote:the main problem that i've got with the cl500m is that i can't seem to get the mill head to stay put.

slotting out a hole, the damm thing either jumps to the side or wanders off line.

its not the job thats moving, its the mill head! any advice would be welcome.
When I started started milling my Smithy 1340, I had the same problem. An easy fix, I just made a longer handle for the two capscrews that locked down the mill head to the column. The wrench thing that came with it was hardly enough to keep things from moving around.

You might start there....

Bill
Today's solutions are tomorrow's problems.
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: endmills/slot drills

Post by Harold_V »

johnnyone wrote:the main problem that i've got with the cl500m is that i can't seem to get the mill head to stay put.

slotting out a hole, the damm thing either jumps to the side or wanders off line.

its not the job thats moving, its the mill head! any advice would be welcome.
If location or size is critical, don't cut slots with one pass. Use an undersized end mill, opening the slot with material remaining on both faces. You can then take independent cuts on each side, controlling location and size (as well as finish). This is true of heavy mills, too, not just light weight machines. It's just a matter of degree.

If you MUST make the cut with just one pass, do not use a four flute end mill. The leading flute will cause deflection of the tool (flexing of the machine) and cut the slot off location. A two flute limits the deflection, but it is not eliminated.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Torch
Posts: 1684
Joined: Wed Mar 17, 2010 7:58 am
Location: Muskoka

Re: endmills/slot drills

Post by Torch »

johnnyone wrote:slotting out a hole, the damm thing either jumps to the side or wanders off line.

its not the job thats moving, its the mill head! any advice would be welcome.
That's exactly what I was talking about. Make sure the column is clamped tight (eg: use Bill's longer handle, a socket wrench, a cheater bar on the handle, whatever...) and limit your depth of cut, especially when using a large diameter endmill in hard material. Harold is also right-on (as usual) regarding the number of flutes. The idea here is to reduce the amount of force torquing the column and/ or increase the amount of force resisting torque at the column.
Post Reply