What to look out for on shank size when buying

Hi,

I have lots to learn and this includes learning from my mistakes when I bought from a well known auction site 2 off 6mm shank end mills of 1.5mm and 2 off 6mm shank 2mm cutters. When they arrived yesterday I could see they were made in China. My Sherline mill has a 6mm end mill holder so o thought it safe to buy. But only one of each size fitted, obviously there are tolerances but you would expect a 6mm shank to fit in a 6mm holder...would you not?

I have been also looking for reamers , here they state a tolerance but I went back and looked at the ad for the end mills and nothing was stated as to tolerance other than 6mm.

Can any one put me wright as to where tolerances such as H7 are stated in relation to cutters do they refer to the shank or the cutter.

Chris

It refers to the hole that the reamer will make which in the case of your H7 will be slightly larger than nominal. In neither case does it apply to the shank.

Stick with buying from a known supplier of imported tooling or brand names.

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Just so that Chris does not get lead too far astray, Barries link actually shows an "h6" tolerance this refers to the male shank, tolerances with a capital H refer to a hole.

Easy way to remember is H = Hole and h = Shank

This is why the H7 that you saw referred to the Hole size the reamer would produce

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Really appreciate all posts will study further tomorrow...trhanks Guys

Chris

Have you measured the shanks?

Yes the bigger one is exactly 6.00mm the smaller 5.96mm and the end mill holder near enough spot on 6mm

Chris

Edited By Chris TickTock on 02/07/2020 15:35:05

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“near enough spot on 6mm”

That would suggest an interference fit ... or at least a very close push fit :

I mean no offence, Chris; but is it just possible that you have collapsed the collet slightly, by holding undersize stock in it ?

[assuming that the collet doesn’t have a stepped bore]: May I suggest that you remove it from the machine and try inserting the cutter-shank from the rear ... just as a check ... If it has closed-down a little, this should be an easier fit.

MichaelG.

Michael, by "end mill holder" I assumed a Weldon shank type holder with fixed hole dia.

Edited By JasonB on 02/07/2020 18:59:09

Chris

The bore of the cutter holder will depend on method of manufacture, if it's reamed to size it may be a little under, especially if an H6 reamer is used, the 5.96 should be OK, but you may need to heat the holder to engage the 6mm diameter cutter it should be usable and likely have less run-out than the other cutter.

Emgee

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Sorry Jason ... I mistakenly thought Chris was using Sherline collets

Probably best if I keep out of the disccussion
... I don’t really like the Weldon type of holder anyway [*], so would probably learn little of interest from Chris’s adventure.

MichaelG.

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[*] before anyone asks : the requisite tolerances seem ‘aspirational’

See here: https://sherline.com/wp-content/uploads/2015/11/3079inst.pd
 

Edited By Michael Gilligan on 02/07/2020 22:24:23

Hi Chris, I'm a bit late to this thread.

I use Sherline 6mm and 10mm end mill holders all the time.

Like you, I initially got some cheap cutters that had an undersized shank, a sloppy fit with lots of run-out.

Now I get all my end mills from the "CNCpoorboy" ebay shop. Select their HSS Cutters and put them in price order, low to high.

You will see a whole range of plain flatted shank end mills of all sizes and flute count. I get the 3 flute type and use them on silver steel, mild steel and brass with success.

They are generally British made, Osbourn or Clarkson and they fit in the holders with a nice satisfying push fit. I have yet to break one.

Under 6mm are less than a fiver with postage and always very quick delivery. They are also good for quality 4 facet stub drills and carbide cutters. I've got a few reamer from them as well.

I have no affiliation with the company but I've used them for about 3 years now and everything I've got has been top quality.

Cheers

Steve

+1 for Cncpoorboy quality and prompt delivery too!

l have no connection either

Dave

I had a similar problem when I was using Clarkson Autolock screwed shank cutters. Included were some special Weldon adaptors for 6mm plain shank endmills. These adaptors had a 12mm screwed shank which fitted the Autolock in the normal way. I tried and failed to get 6mm solid carbide endmills into these adaptors. Because the adaptors were case hardened with exactly 6mm holes, the 6mm cutters would not fit. There has to be a certain clearance. I believe the adaptors were intended for use with the 6mm throwaway cutters which were common at the time which must have had shanks in the region of 5.99mm.

I have bought lots of milling cutters and twist drills from cnc poorboy.

Edited By old mart on 06/07/2020 18:40:21

One of the best eBay sellers, like others have said all good tooling and pretty vast choice with reliable usually next day delivery, been using his bits for many years now.

Emgee

Thanks Steve will give them a whirl.

Chris