2" deep slot

I need to machine a slot .5" x 2.9" thru in a steel block 2" deep.

I think the longest end mill is a long series which can cut to 1-1/2" deep, so I can't break through.

I did think about chain drilling it out then milling from both sides but am concerned the drill will wander off and the two halves won't join cleanly.

I'm using a Warco WM14. Does anyone have any recommendations for how to do it?

A quick look at the Drill Service website shows a long series 1/2" endmill with flutes that are 49mm long. That's almost 2". It doesn't matter if you go a bit deeper than the flute length, provided that you've cut the upper part of the slot to full length first.

I'd probably go for a carbide cutter, as they're stiffer than HSS. I'd rough out as much of the slot as possible with drills a bit under 1/2". I'd also use a centre cutting tool and plunge cut at the ends of the slot first to get a clean finish.

Andrew

Drill a hole right through one end of the slot as your first operation, ideally with a long slot drill (i.e. two flutes) in the mill with the table stops set for the ends of travel. Now use plenty of suds to wash the swarf you make as you cut the remainder of the slot down the hole you just made and out of the way. It's nigh on impossible to keep a slot as deep as this clean of swarf if you go in blind, and it makes a.big difference to the finish if you keep chumping on swarf and may break the cutter.

You can blow the swarf out with the airline, but it's messy, noisy and inefficient.

Interesting my predictive text failed at "swarf". What use is that to an engineer!

Rgds Simon

"I need to machine a slot .5" x 2.9" thru in a steel block 2" deep.

I think the longest end mill is a long series which can cut to 1-1/2" deep, so I

can't break through."

Look in J &L advantage April 2016 page 10 .
12 mm mm HSS-e flute length 53 mm JDCAA-22112K uncoated
@ £8.99 +vat or TiCN coated JDCAT-62112M @ £12.60 +vat,
Both 4 flute centre cutting.

There is an additional one off per order postage charge with J & L .

John

Cameron,

Just a thought [because we don't know what the item will look like] ... Would it be possible to 'fabricate' the slot, by making the item in two, or more, pieces ?

MichaelG.

Thanks Gents - I will try with a longer end/slot mill as suggested. Appreciate your suggestions for where to buy also and trying to keep the slot clear of as much swarf/chips as possible.

Michael - unfortunately the part needs to be made from 1 piece.

Does the slot need to be 0.5 all the way though? If not cut half way with a wider cutter the cut through with the 0.5.

Just a thought, draughtsmen draw the simplest way unless they think of how to produce it.

Howard

Hi Cameron,

I've never tried to machine a narrow'ish slot quite as deep as that but if you know anyone with a shaper - then a tool similar to a heavy duty parting-tool might well manage it and is the simplest solution. A bit like 'linear' parting. I also use slitting saws for deep, very thin slots but my s/saws are mostly only 3" diameter, so wouldn't handle this case. I do have larger diameter side and face cutters (for my big horizontal mill) that could probably be used but obviously this is a very much meatier machine than your smaller vertical mill.

However, I think you should look at these alternatives (to using a long reach mill) as although it wouldn't be done "in industry" - anything that works in practice is usually OK by me. In this case, either a large diameter saw or face cutter held in a suitable mandrel would probably work. Whatever you use it would have to be done in multiple passes of course, just nibbling away at the work piece - very light cuts but I assume time is not an issue for you in this case.

Just a thought.

Regards,

IanT

Sorry Cameron,

Just re-read your post and realised this is a closed slot you are referring to - so my suggestions are therefore nonsense and less than helpful. My apologies.

Regards,

IanT