[PROJECT] Clamp Knurling Tool

[the penguin]

(01-03-2015, 06:53 PM)TomG Wrote: How did you manage to dull two end mills on it?

Tom

I've dulled more than one end mill, trying to take a skim cut, at times it is worse for the end mill, than taking .050" pass, you want the end mill to cut, not rub against the work piece.

[EdK]

(01-03-2015, 06:53 PM)TomG Wrote: .... 

How did you manage to dull two end mills on it?

Tom

Tom,

I've not quite figured that out yet. I started out taking .010" DOC and it seemed be working OK so I increased it to .015" DOC until the end mill started getting dull so I changed it out with a very nice made in the USA end mill made by OSG and that eventually became dull. These two end mills had barely been used so I was, and still am, a bit perplexed as to what was going on. That's when I decided to try the face mill. I used your chart for SFPM and RPMs so it should not have been a problem. Needless to say, if you add the cost of two end mills that's one expensive knurl holder blank.  

Ed

[TomG]

Are you sure that stuff is 1018?

[PixMan]

I think the most common mistake made in cutting metal is that of being "too easy" on tools in regards to overall material removal rates. The tools tend to fail primarily from "rubbing them to death" long before they would have been killed using deeper depths of cut and higher feed rates.

That said, 1018 steel seems to have just enough carbon in it to "work harden" a bit when tickling it with light cuts and slow feed rates.

Ed, were those end mills made of HSS or carbide? What diameter and rpm was used? I know the big variable here is feed per tooth (or inches per minute, etc) because your machine is without any power feed of known values. You just need to keep the tool working a little bit. The 1018 steel won't get particularly hard, but it can be very abrasive on tools if you don't keep them working a bit.

[EdK]

(01-03-2015, 11:13 PM)TomG Wrote: Are you sure that stuff is 1018?

Tom,

Yes, it is one of the few pieces of stock in my stash that I bought in person from a reputable local supply house. I tried a couple of different types of cutting oil but found that no cutting oil gave me the best finish. It seemed very gummy and would gouge rather than cut.

I'll use those dull end mills for side cutting only since just the bottom .015" or so is dull.

Ed

[EdK]

(01-04-2015, 10:04 AM)PixMan Wrote: I think the most common mistake made in cutting metal is that of being "too easy" on tools in regards to overall material removal rates. The tools tend to fail primarily from "rubbing them to death" long before they would have been killed using deeper depths of cut and higher feed rates.

That said, 1018 steel seems to have just enough carbon in it to "work harden" a bit when tickling it with light cuts and slow feed rates.

Ed, were those end mills made of HSS or carbide? What diameter and rpm was used? I know the big variable here is feed per tooth (or inches per minute, etc) because your machine is without any power feed of known values. You just need to keep the tool working a little bit. The 1018 steel won't get particularly hard, but it can be very abrasive on tools if you don't keep them working a bit.

Ken,

The end mills are HSS, 1/2" diameter, 4 flute and I used about 960RPMs per Tom's chart. I don't think I could have gone any deeper on DOC without the mill complaining. I probably did feed to slow and maybe that's what caused the problem. I think I need to bump up the priority on the power feed. I have everything for it but just haven't taken the time to make the parts. I think I'll finish the knurl holders and then divert to the power feed project.

Ed

[Sunset Machine]

(01-04-2015, 10:21 AM)EdK Wrote:

(01-03-2015, 11:13 PM)TomG Wrote: Are you sure that stuff is 1018?

Tom,

Yes, it is one of the few pieces of stock in my stash that I bought in person from a reputable local supply house. I tried a couple of different types of cutting oil but found that no cutting oil gave me the best finish. It seemed very gummy and would gouge rather than cut.

I'll use those dull end mills for side cutting only since just the bottom .015" or so is dull.

Ed

Nothing wrong with taking that .015 off with the bench grinder.  When it's close, put the endmill in the mill, and with a scrap of paper under each point use a stone on the high one to bring them all level with each other. I use these as "roughers"..

It's somewhat like sharpening drill bits - the big ones are easy, the small ones not so much.

[EdK]

(01-04-2015, 10:53 AM)Sunset Machine Wrote:

(01-04-2015, 10:21 AM)EdK Wrote: ...

I'll use those dull end mills for side cutting only since just the bottom .015" or so is dull.

Ed

Nothing wrong with taking that .015 off with the bench grinder.  When it's close, put the endmill in the mill, and with a scrap of paper under each point use a stone on the high one to bring them all level with each other. I use these as "roughers"..

It's somewhat like sharpening drill bits - the big ones are easy, the small ones not so much.

That's a good idea, but I'm not visualizing what the scrap of paper is used for.  

Ed

[Sunset Machine]

Sorry I wasn't clear - the ends of the teeth will be different lengths unless you're better at hand grinding than I am. With the endmill in the mill, the scraps of paper go between each corner (the corners that were dull) and the machine table. Tug on each one to see which one is long. Use a stone to adjust its length until they are all the same, with the endmill still mounted in the mill. It doesn't take much, you're just dealing with the corner of the endmill. A stone can take off quite a few thou with just a few licks, just keep in mind the geometry (clearance, mostly). You can use an indicator too. It affects the finish - one long flute will leave a deep swirly.

[EdK]

Well, this project comes to a screeching halt. I went to cut the blank for the two knurl holders and I cut on the wrong side of the line for one so it's too short. After all the headaches milling this blank I think it's time to take a break from it and start working on the power feed for the mill. I can't believe such simple parts are causing me such pain.

Ed