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Milling arbor sans keyway?

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Robin03/07/2021 10:33:09
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594 forum posts

I bought a new Warco HV mill and I love it to bits, lots of bits, it is all in pieces but slowly coming back together.

It came with two horizontal spindles, 22mm and 27mm.

The 27mm has a keyway while the 22mm has none.

Is that normal? I have no experience.

I notice that gear cutter bores seem to depend on the Modulus. At M2.75 they make the leap from 22 to 27mm bore. I wondered if perhaps the smaller sizes need less torque? Seems unlikely.

Perhaps you are expected to cut your own choice of keyway. This could be catch 22 if all the milling cutters that might cut the keyway are bored 22 because they are considered pathetically small out there in the real world sad

RDG tools have a 1" INT50 spindle that would fit and lots of DP size cutters to go on it. Unfortunately, they forget to say if it has a keyway and I have become suspicious. Also, does INT50 imply it wants a 40mm support bushing at t'other end?

Too many questions thinking

Andrew Johnston03/07/2021 11:11:35
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6679 forum posts
701 photos

All my arbors, metric and imperial, have keyways. Small arbors, as used by clock makers, may dispense with the keyway but not otherwise. The bore of a cutter depends, to some extent, on the OD of the cutter. Smaller cutters have smaller bores so a sensible depth of cut can still be used. Are you sure it's INT50? That's a serious size taper normally found on large mills. My 3500lb horizontal mill is only INT40. Outer support is dependent upon the cut rather than taper size. i almost always use outer support on the horizontal mill, even with small slitting saws.

Andrew

Robin03/07/2021 11:17:57
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594 forum posts
Posted by Andrew Johnston on 03/07/2021 11:11:35:

Are you sure it's INT50?

No it is INT30, I have a problem with my brain sad

Dave Halford03/07/2021 11:27:17
2102 forum posts
23 photos

The Warco ad claims ISO30, which was fitted on some late Centec 2B machines. Power output is similar as well.

The Centec does not require a keyway, the friction from the arbor nut is sufficient to prevent slip even on a 3/8 wide cutter.

Roderick Jenkins03/07/2021 11:33:40
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2201 forum posts
616 photos

My Sharp mill has a 1" arbor without a keyway. I haven't had any problems cutting 20 DP gears.

rolls milling.jpg

Rod

Howard Lewis03/07/2021 11:38:41
6317 forum posts
15 photos

The 22 mm arbor is probably intended to carry Slitting Saws (They uesed to be 1 inch bore, but with the march of Mtrication, Slitting Saws now tend to be 22 mm bore. )

A Slitting Saw should never be used with a key.

The saw is thin and cannot withstand the forces produced by a key should the saw jam. Without a key, the saw can stall while the arbor still rotates.

As an Apprentice, I had a narrow escape, when walking past a machine where a fellow had used a key, despite the warning from our Instructor. The cutter exploded, half still rotating on the horizontal arbor, while the rest of the saw rained down from the roof in small jagged pieces.

Howard

Robin03/07/2021 11:45:49
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594 forum posts
Posted by Dave Halford on 03/07/2021 11:27:17:

The Warco ad claims ISO30, which was fitted on some late Centec 2B machines. Power output is similar as well.

The Centec does not require a keyway, the friction from the arbor nut is sufficient to prevent slip even on a 3/8 wide cutter.

The Warco Ad confused me. ISO30 lacks the driving dogs, whatever they are called, so this is INT30 which has them. There is also BT30 for auto tool changers but it isn't that either.

I think I have to cut the keyway to keep it cushty, but if I can get away without then I am safe to buy a set of involute cutters and see how big the keyway needs to be.

I have a 6mm broach so I am hoping it's a 6 smiley

Robin03/07/2021 11:54:38
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594 forum posts
Posted by Howard Lewis on 03/07/2021 11:38:41:

The 22 mm arbor is probably intended to carry Slitting Saws

A Slitting Saw should never be used with a key.

Fascinating. You might think it would make more sense to omit the keyway from the saw rather than the arbor.

Could I be up against some weird H&S thing?

Robin

Robin03/07/2021 11:58:32
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594 forum posts
Posted by Roderick Jenkins on 03/07/2021 11:33:40:

My Sharp mill has a 1" arbor without a keyway. I haven't had any problems cutting 20 DP gears.

rolls milling.jpg

I love it. I feel a deep need to cut gears, probably just a blood clot but it still has to happen thinking

Journeyman03/07/2021 12:07:27
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1174 forum posts
236 photos

A paragraph from my website regarding ISO etc. tapers

Larger machines may well come with ISO or similar tapers, image (6). These are non-locking tapers having a standard slope of 7:24 (≈16° included angle). There are several different systems all using the same angle taper but with different draw-bar threads, ends and flanges so it can get confusing searching out the right thing. There are also several size ranges 30 to 60 but by far the most common is 40, there is a vast range of industrial tooling made with this taper.

  • ISO, NT, NMTB, DIN2080 - short parallel section at small end. Equal drive slots.
  • CAT, CV, V-Flange, DIN 69871 - no parallel section. Unequal drive slots.
  • BT, MAS403, DIN6383 - no parallel section. Equal drive slots.

This video by Mattias Kristiansson throws some light on the subject. The torque for these tapers is transmitted by a pair of dogs that match the slots in the flange. Some of the holders are designed for use with pull studs for CNC automatic tool changers. The studs can be replaced by a draw-bar for a manual machine.

John

Robin03/07/2021 12:53:26
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594 forum posts
Posted by Journeyman on 03/07/2021 12:07:27:

A paragraph from my website regarding ISO etc. tapers

Tell me about it frown

I have a couple of ISO30 ER32 collet chucks that I bought before I realised Warco had it wrong.

I will probably give them to my son, he can flog them on that auction site and make a few quid.

There are some tasty, low overhang, INT30 ER32 chucks out there. I got one and am looking for another.

Robin

Edited By Robin on 03/07/2021 12:53:53

Baz03/07/2021 13:20:05
757 forum posts
2 photos

When I was an apprentice I was taught that anything over quarter inch wide was keyed, anything under a quarter inch wide you keyed the collars either side of the cutter, it was not very often we used anything under half inch wide and about eight inch diameter, using Cincinnati, Huron or Milwaukee horizontal mills. Nowadays I have to make do with a little Sharp mill, same as Rod Jenkins, and I have never had a cutter spin or break on it, like Rods machine my arbor is plain, no key way.

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