14.5mm end mill equivalent

Hello

I need a 14.5mm end mill (square cut) - but can’t find one at a suitable price (it will probably be only used once) and don’t want to pay the high cost.

could anyone advise me of the imperial equivalent of this size please? I am hopeless with engineers tables - there may be a more cost effective version more readily available in UK.

many thanks

Margaret

14.5 mm divided by 25.4 = .5708 inches. Nearest inch size std endmill would be 9/16" or .5625". Bear in mind that endmills often do not cut to their exact diameter. If you are trying to produce an exact 14.5 mm hole or slot you may have to make a few cuts with a smaller endmill to reach the desired size feature. Hope this helps.

There is no direct imperial cutter, the nearest would be 9/16" which is 14.29mm

What is it you ar edoing that needs that specific size particularly an end mill as that is not use dfor slots which may have a width or half round end that determines the diameter.

If it is just a through slot use something narrower say 12mm or 1/2" to mill down the middle and then offset each side to bring your slot to width

Thanks Jeff and Jason - the 9/16 route would be perfect @14.29mm because that is the exact size of the tube which needs to fit into the hole.

I am making (or attempting to!) a collar - which will have a 14.29 tube sticking out of one end and a 9mm the other. The reason for using an end mill rather than a drill (on the lathe) is that the collar is only 10mm deep and a drill, with the chamfered end, will leave a cone shaped hole which is no good. With me? Hard to explain.

Another couple of questions before I embark on this madness:

1: would you recommend drilling a pilot hold before the end mill goes in? If so what size?

2: is it ok practice to use an end mill in a lathe? (Milling brass) - rather than a mill? I only have a small hobbyist mill and not sure I have a suitable collett for such a big end mill.

Thank you all - I woule be lost without this forum - you are all a wonderful resource.

Margaret

Margaret,

You will need a slot drill if you want to plunge cut a hole, They have two cutting faces. You can get a cutter with three cutting edges that can also do a plunge cut. You are better off with a slot drill to cut a slot as it will cut to size, An end mill will cut oversize.

Andrew.

Edited By Andrew Tinsley on 18/07/2023 14:42:54

Thank you Andrew!

Would this be no good Andrew? Not sure of the difference between and end mill and slot drill!?

Here you are, Margaret:

https://www.ebay.co.uk/itm/133666139409?hash=item1f1f1f6d11:g:drYAAOSwaKthp94z

Thanks Bill. I have purchased it 👍🍻

Would you gentlemen recommend I drill pilot holes before going in with the 9/16 slot drill? I guess these would have to be drilled with smaller slot drills?

Edited By Clive Brown 1 on 18/07/2023 15:25:12

I would certainly reccommend making the hole as near as possible to the finished size first. A drill could be used to get to 1/2" if you have one, or smaller end mills. Several stages would work fine, but as already mentioned, the hole might be bigger than the 9/16" expected by a small ammount depending on how sharp the last cutter is. Precision holes are normally produced by reaming or boring the last bit.

I would centre drill and then drill, say 6mm diameter, to just short of final depth. Then one could use a ~10mm centre cutting endmill and finally the 9/16" slot drill. Personally after drilling I would use a short HSS boring bar. That way one gets a hole exactly to the size wanted and with a truly flat bottom. Slotdrills and endmills are ground slightly concave on the end.

When using a slotdrill as a "drill" in brass one needs to be careful in case the tool grabs. They are better than normal twist drills (due to a slower helix) but not as good as the slow helix drills specifically for brass and bronze.

Andrew

Thank you gentlemen for your suggestions.

Andrew - could you post a link to the right short HSS boring bar I could use pleaee? Sorry if that’s stupid question - I am very new to this.

Many thanks

Margaret

Would I be better using a smaller slot drill - then using an HSS boring bar to get it to 9/16? Rather than using the 9/16 slot drill?

As you don't have the 9/16" cutter and say you are unlikely to use it again I would the boring bar option

Spot drill then drill say 6mm, 10mm and 12mm or whatever you have and then use a boring bar to bore a flat bottomed hole that can be tweaked to get the fit you want on your tube.

8mm shank bar and a CCGT 060204 insert

Edited By JasonB on 18/07/2023 16:18:36

Though I often use a cutter to open a hole as you suggest this would be a much better way to achieve what you intend. There is no guarantee that an endmill or slot drill for that matter would give you the exact size you seek - you will only know after you have machined the hole - using a boring bar (if used carefully) will.

A small boring bar can be made from a worn slot drill - I have an image somewhere so will try to find it for you.

Tug

A 14.5mm end mill is pretty massive for hobby purposes

I would drill most of it to 12-13mm and then bore

It took a while to find -

The flutes on a slot drill are ground back to leave just one tip and that is then used as a short boring tool.

(The reason this is cutting backwards is that the part being turned is screwed onto the rear part with the inlet tube)

Old slot drills and three flute end mills make ideal 'home made' cutters if you are up for using an off hand grinder

Hope that helps - Tug

How is the one in your picture held in the toolpost, Ramon? In a square profile holder with a slit?