90 Degree end mill

I want to cut a 90 degree V groove in a rectangular block. I have seen videos describing techniques using an 'ordinary' end mill and measuring, mounting the block at a 45 degree angle etc. but it strike me that an end mill with a 90 degree shaped end would be an easier way of doing things. I have searched for 90 degree end mills but the results are almost universally described as 'chamfering tools', are they the same thing or am I using the wrong search terms ?

Chamfering mills are for chamfering! The problem with using one to make a V-groove is that the tip of the tool has just about zero cutting speed, so it will be ploughing rather than cutting. Even if you don't break the tip it will likely leave a poor finish. Tilt the block, or at least use a slitting saw to cut a deep groove first so that the tip of the chamfering cutter isn't cutting. Look at a V-block, there's normally a slot at the bottom of the V.

Andrew

Thanks Andrew, I hadn't thought about what would be happening at the tip of the tool. I can't run a slit down it so it looks like I will be tilting the block and doing some marking out. I needs the practice as milling is new to me

You could possibly rough out the Vee with a series of steps done with decreasing diameter milling cutters finishing with say a 3mm one to put the groove into the bottom on the vee much like the saw would. Followed by a pass with your chamfer tool to cut the corners off the steps.

Not tried it but another option may be to grind a little off the end of a chamfer cutter so that the edge will have some peripheral speed, this would leave a slight flat at the bottom of your Vee which could have a 3mm slot milled in or depending on what is going into the Vee you could knock the corner off of that.

What are you cutting ? Might get away with a wood router Vee tool if it is aluminium.

Thanks Jason.

I am making a tool to hold round bar so I can drill holes through it at 90 degrees to the axis. The block will mount in the tail stock with the round bar clamped in the V. I am using a piece of square stock mild steel and intend to mount it on a blank end arbour.

This is practice for me in thinking about the design and the order of machining steps. There will be a hole through the V and the centre of the block to provide relief behind the bar for the drill to break through. Currently trying to decide whether to drill the hole and machine the pocket for the blank end arbour before or after I cut the V. It is important that the V and the hole coincide at the centre.

This may be of use, though not sure if you really need one now that you have the mill.

Edited By JasonB on 03/06/2018 20:18:29

What you need to search for Nige is a Drill Mill. I got mine on eBay but these folks have them:

**LINK**

I bet this will upset a few, essentially gluing bits of steel!

Sometime ago, I wanted a steel block with a big 90 degree endmilled slot, or at least someone else' design called for such, to which I thought bugger that. I cut a 5mm plate of steel same footprint as block, cut off 2 pieces of thick steel angle of a suitable size web and mounted them side by side with the edges on the 5mm plate. Elicited them in place. Robbie done! I should add that the resulting V was to serve as a guide for toolgrinding so the Loctite was not put under any great stress so would not let go.

Just looked at the price. I paid about a tenner for a 10mm solid carbide Drill Mill on eBay so I got a bargain!

Jason: That is exactly what I am making except my block is rectangular to give me reasons to practice using use the 4 jaw chuck

My experience of using a drill mill type of tool for engraving was poor. I kept breaking the tips even with quite low feedrates. I came to the conclusion that the 5000rpm max spindle speed on my CNC mill simply wasn't fast enough when using the tip of such tools.

Andrew

The 90 degrees is not a requirement - the only thing is it needs to be symetrical. For anything square that you might want to drill in it (if a 90 degree V) you should have some relief at the bottom of the groove, so you might just as well add it at the start.

There are other ways of fabricating the part. Depends on the size of it, really.

Fabricating kind of defeats Nige's purpose of using it as a project to get used to using his mill...

Neil

More info on Drill Mills here for anyone interested.

**LINK**

And cutting speeds

**LINK**

A Drill Mill is not the same as a Spotting Drill by the way.

Stuff like this does come up on eBay from time to time at a good price and very handy to have if you can get one.

MSC J&L list these , try part no's FAC- 99064H , FAC-99116H and FAC-99140C

John

If you want to cut something softer than steel you could try this.

**LINK**

I have cut the V groove again. I decided the block of mild steel hung out from the arbor more than was necessary and I wasn't too happy with the depth/width of the first V groove I cut. So I took a slice off on the band saw and remounted the block and faced it again this time with an HSS tool with a slight curve to the nose which gave me a much nicer finish.

I have had another look at one of Tubal Cains videos on cutting V grooves where he describes how to calculate the position for the milling cutter from first principles using a bit of trig' and the scales on the X and Z axis. It is a little complicated to start with but transferring the knowledge to actual practice made more sense of the technique. I had a centre line scribed on one face so I had a visual clue as to whether I was getting it right. Doing it this way you have to keep careful track of how many turns of each handle you use as I found out !!

I wanted 10 mm faces on my Vs and having got the cutter centred I decided to take 0.5 mm cuts in the Z & X axis simultaneously with the idea that my V would 'grow' symmetrically from the centre line. Once I had taken a couple of cuts I could see that I was about 1.0 mm 'short on the Z axis cut which I put down to miscounting turns and at one point winding the Z axis the wrong way and having to 'go back'!! Having put that right it was an easy finish with a few more passes of the cutter.

And here it is, though it still till needs the clamping plate and its associated threaded holes making.

So what did I learn:

• That I have to get to know my machine better, which way to turn the Z axis handle will soon become second nature I'm sure.
• Every minute of thought, preparation and checking is worth it.
• I could have taken bigger cuts than the 0.5 mm (20 thou) ones i was taking.
• I can see how damn useful a DRO will be !

Having the tooling this is what I would use. A left hand and a right hand 45° cutter mounted back to back on a mandrel. If you had lots of these grooves to cut some used 90° or 45° cutters would be worth looking out for.

Martin C

I’ve got a cutter that looks like that (but one piece) Martin. Not sure of the angle though. I actually bought a pair of them for a particular job over 15 years ago but not used them since.

This picture shows the difference between the cutters. The two on the left are Spotting drills, the one in the middle is a Drill mill and the one on the right is a Chamfering mill.