PM935TV

[davidpbest]

Thanks.

 

[wrmiller]

It isn't stupid at all. In fact, a genuine RF-45 is even rated for drilling up to 1.5" diameter in mild steel. This is with a 1-1.5 HP motor.

My test puts RPM's at about 100, which is in the vicinity of where we believe the 833TV to be weak. It is a perfectly reasonable test. I have drilled dozens of 11/16" holes on my PM25-MV in low range into 316 and Grade 5 titanium 1.5" deep. This is with a pilot hole big enough to clear the larger drill chisel/web. No issues at all, asking a knee mill to do a little more isn't so much of a leap. This was before I had a lathe in the home shop, obviously now it is much faster to drill the same hole on a 2HP PM1236.

OK, maybe I shouldn't have said 'stupid'. I'm just of the opinion that if I'm having to drill holes that large (I don't), then I'd own a much beefier machine to keep stresses on the machine lower. But to each their own.

And comparing a low-speed geared drill press to a 833TV? Really? Seems apples to oranges to me, but whatever.

 

[bakrch]

OK, maybe I shouldn't have said 'stupid'. I'm just of the opinion that if I'm having to drill holes that large (I don't), then I'd own a much beefier machine to keep stresses on the machine lower. But to each their own.

And comparing a low-speed geared drill press to a 833TV? Really? Seems apples to oranges to me, but whatever.

I agree, it may seem like that, but we do not know how it will perform under the conditions until we test it.

If you are able to give us the info we need as to not even bother with such a test, please do so!

 

[wrmiller]

I'd never compare the two, sorry.

 

[luxige]

Before you make a decision, don't discount the larger more advanced benchtop mills with their factory supplied base. READ the attached before you decide on a PM-935. If you'd like more information, let me know.

Thanks, that’s a good read, and informative.

 

[davidpbest]

Thanks, that’s a good read, and informative.

Looks like you read the first draft, which I've now updated with fresh and accurate data with respect to the PM-833TV. Here is the link to the new document if you're considering that specific model. Click here.

 

[petertha]

Sorry for the tangent, I haven't seen that FS wizard app before. Has anyone seen a numerical comparison between an annular cutter to a typical 'full hole' 2-flute drill? I find myself grabbing AC's more often now for through holes. I like how they cut. My collection are only 1" length but starting to eye a 2"set... you know... precautionary thing....just in case of a Zombie attack.

 

[mksj]

Annular cutters, you need to keep the speed down in the mill, smaller cutters 400 RPM maximum. You want to keep a constant pressure through the boring process, do not peck at the work. Use a lubricant for most metals, assuming the exception would be cast iron. I also use them on the lathe, a real time saver over drilling. Limit is the depth, I recently built a spider and used a 1.25" 2" depth annular cutter to punch out the center for a 1" boring bar. I used the annular cutter from both sides, around 250 RPM (I go a bit slower with the lathe, but I would use around 225 RPM for a 1.25" MT drill). I went with 2" depth annular cutters for the ones that I have. I use them mostly in steel like 1045, 4140, plate, etc. They cut very nicely, I modified a 3/4" end mill holder to hold them on my mill.

 

[petertha]

Your comments are spot on to my experience, including the don't peck recommendation. That might be one downside. When I let off to allow chip termination that was getting kind of snarly, it can take some fiddle farting to get the cut established again depending on the material. Aluminum I wasn't too worried about but the multiple steel strings were starting to get into places they didn't belong.

Another nice thing is when the material is valuable, you get a nice core of material to do something with as opposed to making a pile of chips. This was the case with a chunk of bearing bronze.