Deep slot cutting in lightweight milling machine

[Fazerruss]

I feel your pain. It took an absolute age to mill these slots when I made this angle plate. It's only 12mm thick too.




And yes there are plenty of us lunatics messing about with machinery in Yorkshire. I'm near knottingley.

Ps this plate was also a mount for my rotary table so I could position it on its on it's side.

 

[Allthegearnoidea]

Hi Faz

That’s a really nice angle plate. Is that a combination horizontal vertical mill. Looks a lovely machine what make is That?

Chris

 

[Fazerruss]

It's erm, erm a Tomport Bridgesenior! Horizontal
Tom senior with a vertical Bridgeport cherrying head attached.
Here's my conversion build restoration thread.....

http://www.mig-welding.co.uk/forum/threads/theres-going-to-be-a-wedding-sort-of.69529/#post-971363

 

[Allthegearnoidea]

That is a lovely job Faz. :-)

 

[Bill Edwards]

Well having read through this it's made me really glad for my machine being a big heavy beast, at almost 3 tons. When it comes to machining metal away I soon get very bored.

My interest won't be what depth and speed can the machine manage, but what depth and speed can a milling cutter manage before it turns into lots of little pieces!

 

[Allthegearnoidea]

Hi Bill so what depth before the excitement?

 

[atconut]

get some r8 collets throw the clarkson away (i see you use one aswell Faz) get the tool into the spindle you will notice a massive difference. think of a lathe you would'nt have the tool sticking out of the tool post four inches. you're just asking for chatter with all that stickout. you may get away with it on a bridgeport but on a small mill you have to try to keep everything as rigid as possible

 

[atconut]

Here's a vid that explains why it's better to take a deeper cut at a feed that suits your machine. ignore the fact he mentions a Bridgeport the principles are the same. by only taking very shallow cuts you are not getting enough flutes of the endmill engaged. rigidity is very important so keep your tool stickout as short as possible food for thought let me know how you go when you get some R8 collets

 

[atconut]

if you watch this guy explain about cutter engagement maybe you will understand why you get chatter. also try using a tool with more flutes that way the gap between flutes is smaller. am i babbling on?

 

[Bill Edwards]

Hi Bill so what depth before the excitement?

Don’t know as I’ve yet to have it running.
But at 2.8 tons and a 7.5kw three phase motor I know it’s not going to be the mill letting me down!

 

[julianf]

If you are, effectively, performing a roughing cut with your drill, are you able to plunge to full depth and then cut using the side rather than end of the cutter?

I always make a finishing pass on CNC alluminium routing. End mill goes down in multiple passes, comes up, plunges to full depth in the center of the holes, moves to the edge, and skims the last 0.25mm.

That way I don't need to worry about machining marks or but from the previous cuts. I do it for coametics, but it may be something you can consider, providing you can take away enough material with your roughing pass on the drill press.

 

[Allthegearnoidea]

Hi ATconut.

Thanks for the advice on the R8 collets, is it the draw bar that acts to tighten the collect around the cutter. Do these type of collects take a tool without the screw threaded end or the notch in the side of the shank. I think the R8 collets May be a good idea to reduce the stick out from the spindle etc.

Hi Julian

I tried cutting by repeated plunging and also conventional milling. I think the stepped plunge cutting removed bigger bites and was faster but just wonder if it was a unorthodox method. For the first plunge I had already drilled a hole under the face of the cutter as I was using an end mill rather than a slot drill.


Many thanks for the comments

Regards Chris

 

[atconut]

Hi the R8 collets are pulled into your spindle taper with the drawbar yes you can still use the threaded shanked tools you have they will grip any tool with a round shank. the clarkson collet holder you have will be held in by the drawbar so you should be able to use that. you will notice a huge difference when you reduce the stickout i know i did, a set of R8 collets will be a very good investment. if you are unsure what to do pm me i will gladly lend you a collet and couple of cutters for you to try. i'm not a million miles away glad to help

 

[atconut]

by the way you don't have to buy a full set of collets you could just buy individual collets for the cutters you use the most

 

[Allthegearnoidea]

Hi Many thanks for the advice on collets. I will probably have a look at the Collet sets next week as the Clarkson Arbor I have was pretty poor quality anyway. I probably should have gone down the collet route first but my old machine had a nice morse taper clarkson arbor made by vertex and was better quality than my later R8. Thanks for the kind offer the loan of a collet anyway.

Best regards Chris