2x72 belt grinder build

[rabler]

Another photo bomb.

Made the base for it today. Started by one of those fixturing setups that looks like something of a kludge. Rotary table on the mill. Fixture plate on the rotary table. Bandsawed parts stacked together on top of 123 blocks. Edge finder at each layer to keep everything on center of the rotary table. Started by roughing the straight edge along the bottom, as I need those to be the right distance from the 3/4" pivot shaft hole. Then drilled that pivot shaft hole, and then the hole for the locking pin.



Back to the rougher and smoothed out the outer radius, a cosmetic feature.


Then over to the grinder to clean up the rest of the sides, then the upside down handheld belt sander (gee, I need belt grinder) to clean it up a little bit before welding.




My CAD drawings call for a smaller base plate (4" x 8.5"), I went with 6" x 10" to give it a little more stability. I'm using 6" wide material, and welding right at the end is a little more difficult. So there may have been some laziness (fabrication enhancements) to that design mod. I cut a piece of scrap tube and clamped it between these pieces at the desired spacing, and did my best to get it square, tacking it up first and re-checking.







Got the shaft drilled and tapped for 3/8" bolts using the lathe, tapped out the locking pin hole, and put it all together.

 

[woodchucker]

If I were machining to square shoulders on both sides, and with a steady rest involved, I would shy away from the trigon (WNMG) tooling because the insert is mounted with a negative rake and adds a significant amount of tool pressure toward the spindle centerline. My first choice would be to use a right- and left-handed tool with CNMG inserts - this will be freer cutting than the WNMG and have less tool pressure. With a neutral hand tool like your MSDNN or the SCMCN you're thinking of getting, you can't machine to a square shoulder with either of those tools, so you'd be left trying to cut the shoulders with a parting or grooving tool. Hope this helps.

David, isn't a cnmg negative rake as well?
If you were looking to plunge , why not plunge with a parting tool?

I agree, I don't think a WNMG is a plunging cutter. My friend and his co-workers call it a wiper. I like the wnmg for it's finish..
I think the rhombics (diamond shaped) work well working upto a shoulder and into it.
They plunge well, but not great. You need to plunge, then cut the opposite way to relieve the cutting area. I started wondering why Keith Rucker was using them pretty much full time. They are supposedly finishing inserts, but they work well at shoulder cuts. I believe Keith is using a V, I am using a D, I think an F would work too.

 

[rabler]

If you were looking to plunge , why not plunge with a parting tool?

Results in too narrow of a slot. You can't cut axially with a regular parting tool, so if you need a 1.5" wide groove between shoulders, it doesn't really help, you can't get something like a CCMT tool into the resulting slot.

 

[davidpbest]

David, isn't a cnmg negative rake as well?
If you were looking to plunge , why not plunge with a parting tool?

Yes, it is. CCMT is what I meant - sorry, I'm blurry from 24 hours traveling. On such a small diameter shaft with a steady rest, a negative rake toolholder is not ideal - I'd avoid WNMG and CNMG and DNMG for this application.

A "wiper" is a feature of the cutting edge next to the nose radius, and really has nothing to do with the geometric shape of the insert. Some WNMG inserts (and other shapes also) have a wiper, some do not. It is essentially a small flat section on the insert between the long flat side and the nose radius. It can improve surface finish and allow for higher feed rates. But this is getting pretty specialized.



You could plunge with a parting tool, but you are running a big risk if you start moving that same tool laterally along the carriage travel. A grooving tool with a large full nose radius is essentially a parting tool with a very short stick-out and when the insert has a full radius it can be traversed side to side as a profiling tool. That''s why I suggested the Top Notch with full radius insert.

 

[davidpbest]

I think the rhombics (diamond shaped) work well working upto a shoulder and into it.
They plunge well, but not great. You need to plunge, then cut the opposite way to relieve the cutting area. I started wondering why Keith Rucker was using them pretty much full time. They are supposedly finishing inserts, but they work well at shoulder cuts. I believe Keith is using a V, I am using a D, I think an F would work too.

The rhombus-shaped inserts (CCMT, CNMG, CPMT) can all be had in roughing and finishing grades - the difference being the sharpness of the cutting edge, the shape of the chip breaker, and the base material and coatings that are applied.

 

[woodchucker]

Results in too narrow of a slot. You can't cut axially with a regular parting tool, so if you need a 1.5" wide groove between shoulders, it doesn't really help, you can't get something like a CCMT tool into the resulting slot.

yea, you would have to plunge, move , plunge, move, etc. you can move axially with a few thou left to cleanup, but better to use a tool that is meant for turning, and the styles I mentioned above, are thin, and can do it.

I have a HSS that I was given by a machinist when he gave me a kennedy tool box all loaded up. He had made up a wider tool to do what you describe. It could have been a very wide grooving tool. I don't know, I've never used it.

 

[woodchucker]

Yes, it is. CCMT is what I meant - sorry, I'm blurry from 24 hours traveling. On such a small diameter shaft with a steady rest, a negative rake toolholder is not ideal - I'd avoid WNMG and CNMG and DNMG for this application.

A "wiper" is a feature of the cutting edge next to the nose radius, and really has nothing to do with the geometric shape of the insert. Some WNMG inserts (and other shapes also) have a wiper, some do not. It is essentially a small flat section on the insert between the long flat side and the nose radius. It can improve surface finish and allow for higher feed rates. But this is getting pretty specialized.

View attachment 395130

You could plunge with a parting tool, but you are running a big risk if you start moving that same tool laterally along the carriage travel. A grooving tool with a large full nose radius is essentially a parting tool with a very short stick-out and when the insert has a full radius it can be traversed side to side as a profiling tool. That''s why I suggested the Top Notch with full radius insert.

Thanks, I was thinking they were making fun of it, as he, and his co-workers don't like the WNMG. I thought the wiper terminology was a knock..
I like it though.

Thanks for clarifying the CNMG - CCMT, now that makes sense.

 

[rabler]

The Iscar WNMG inserts actually cut fairly well without chatter or other issues. 1018 so a good finish is another question. Of course it is a pretty heavy machine.

 

[jwmay]

You can't cut axially with a regular parting tool, so if you need a 1.5" wide groove between shoulders

I usually just try to read when the experts are consulted. But I figured it's not the end of the world if I disagree. I've used a parting tool for all sorts of turning operations. In, out, left, right, and tapers. I've not had one fail yet.
Most recently, I cut a tapered boss on which to mount my compound. The professional machinist at work was shocked that it worked. Claimed he'd never seen anyone turn with a parting tool before. When the part was complete, I turned the spindle speed UP to 600 something and sliced it off with the same tool. So maybe it's not accepted practice, but it's done nothing but work great for me.

 

[WobblyHand]

I usually just try to read when the experts are consulted. But I figured it's not the end of the world if I disagree. I've used a parting tool for all sorts of turning operations. In, out, left, right, and tapers. I've not had one fail yet.
Most recently, I cut a tapered boss on which to mount my compound. The professional machinist at work was shocked that it worked. Claimed he'd never seen anyone turn with a parting tool before. When the part was complete, I turned the spindle speed UP to 600 something and sliced it off with the same tool. So maybe it's not accepted practice, but it's done nothing but work great for me.

Have to agree. I used a HSS parting tool to make the section between the flanges. At 1/2" spacing, nothing else would fit. Can't get greedy, but at moderate DOC it works fine.