[bobeson]

I just want to share the joy because I can, and receive intelligent feedback along the way. And the forum hasn't let me down yet!

Right on, John, this is the best way to go about projects. I'm glad to see you have the kind of thick skin that will allow you to make good use of forums like this, and the graciousness to share your progress with us, despite the nay-sayers.
Engineering can be fun, and empirical discovery is loads of fun when you can tolerate the downside risks.
Keep on keeping on!

[johnh]

Thanks guys!
I might upload some pictures of my machine before I start, its in real used condition, wink, wink.almost embarrassing. But it follows the proverb, "where there are no oxen the stall is clean, but with oxen there is much profit."

I have looked at a larger machine and there will be one in the future, but that's a much bigger investment in time, money, floor space, LEARNING CURVE etc. and given the size of my needs right now it's not justifiable, but if I can get my Tormach a boost it will go along way for cheap $$$

That being said, it's in want of a complete cleaning and some overhaul. A bunch of the paint has come off from the constant coolant exposure, the elec cabinet needs a couple of good latches to seal it up, I remote the panel long time ago, What I need to do is pull it out into the middle of the shop, yank it off the stand and strip the paint and epoxy paint it. At that time I could flip it over and do the epoxy granite fill, give her the full Monte before putting her back in service. Hybrid Stepper upgrade could happen later easy enough, Since torque goes down with speed, Um, maybe BIG torque motors geared up to bring the IMP of the table up????? Um. OK, lets not go there yet. forget I wrote that!

So I'm still in the plan of attack phase. What I don't have time for is a methodical one variable at a time incremental test and document results development project, what I need to do is the best practices think ahead inclusion of all the best ideas now, that's what I want to do.

Yes it would be advantageous to park the spindle in the same spot and If that's the case I need to buy into a VFD that can do that now.

That would be a VFD with feedback right? $$$

I'm a complete novice in the VFD / electronics area, learning as fast as I can , but my thought was perhaps a macro could be written and invoked with an induction switch and a timing disk with one notch coupled with a slowdown to 1hz or something like that then brake could be applied and bam, the motor should stop in a predictable place every time without the added exspence of a direct feedback VFD. any experienced thoughts?

Given the tools turn on an axis I would have thought that indexing wouldn't change any runout for the better, but the the dogs were an anti-slip or torque transfer mechanism? at potentially 5 HP do you think the BT30 wouldn't slip in its taper? Because that would be a disaster.

thanks for being here guys!

[SCzEngrgGroup]

Spindle indexing for purposes of aligning toolholder keys should be quite easy using the jog function built into nearly all VFDs. All you'd need is an index pulse. Use the spindle jog, and when the index pulse triggers, stop the jog. If the jog is at a low speed (2Hz or so), this should give you more than adequate indexing accuracy.

Yes, the dogs are for added insurance against the the taper slipping. At 3HP, I would not worry about it. At 5HP, probably worthwhile, depending on how you actually attempt to use the 5HP. It is not power, but torque you have to be concerned with w.r.t. toolholder slipping. 5HP at 10K RPM would not be a problem. 5HP at 100RPM would likely be a problem (but you won't have 5HP at 100 RPM...). Drawbar tension is, of course, also a major factor. If you're going with a "grabber" type retention system, rather than a screw-drawbar then your drawbar tension will be limited (IIRC, 30-taper typically requires ~1300 pounds).

Regards,
Ray L.

[R.DesJardin]

John,
I found a thread where a guy made his own pull stud draw bar for BT30's, it wasn't a Tormach but I found it very interesting. Almost seemed simple. Just wish I had more time to try it as I seldom have down time when the machines aren't needed to build something.
I have also wondered if spring tension would hold a BT30 in place without the dogs, does probably depend on hp/torque and MMR. I guess I'll wait here for the results.

[SCzEngrgGroup]

John,
I found a thread where a guy made his own pull stud draw bar for BT30's, it wasn't a Tormach but I found it very interesting. Almost seemed simple. Just wish I had more time to try it as I seldom have down time when the machines aren't needed to build something.
I have also wondered if spring tension would hold a BT30 in place without the dogs, does probably depend on hp/torque and MMR. I guess I'll wait here for the results.

30-taper is little different from R8 in terms of retention - both have the save taper diameter, and taper angle. The 30-taper has a slightly longer taper. Because of that, it can eb retained with less drawbar tension compared to R8, for any given torque. So, at 1.5HP, 30-taper would work just fine with the same drawbar tension as R8. Above 1.5HP, and especially above 3HP, things get a bit dodgier, hence the dogs - cheap insurance. With the dogs, drawbar tension can be reduced, since you only need enough to ensure the holder cannot pull down, hence the typical ~1300# tension used for 30-taper systems. More never hurts, just to ensure there is never any rotation of the holder in the spindle, which can lead to fretting. The down-side is, 30-taper using pullstuds requires a long-travel spring system to release the tool. This means a looooong spring stack. Typical pullstud systems have upwards of 100 Belleville springs to get the necessary tension and travel, with the springs buried deep in the spindle itself.

Regards,
Ray L.

[R.DesJardin]

Here is a link to one of those builds, BT30 Build I just Googled homemade BT30 spindle.

[johnh]

Hey CNCCockBook!

read your blog which turned me onto the Sumitomo drives, found a 10hp one on ebay for $345!!!!!! Yeah man, this is perfect and not too large! its the HF4302-7A5 so I'll have the feed back possibility, AND I can feed it 1 phase no problem and handle all 5 hp with no sweat. Saved me about $400


jh

[johnh]

Nice BT30 spindle link thank! had not come across this one yet. This and another thread has confirmed I can get away with a single top bearing, which will be advantageous in many ways, packaging, cost, simplicity.

jh

[johnh]

Two Questions

to run at low rpm with high torque I will need to provide forced air cooling from an auxiliary fan, does anyone have a clue as to the CFM that might be required? Looking at a bunch of axial fans to mount on the bell end, the other benefit I can remove the inefficient centrifugal club on the end freeing up some more power to the spindle and more easily mount the encoder.

Which is the second question

any encoder recommendations for 8000 rpm? I would think resolution is not super important, also I'm thinking indexing pulse is more important if I want to park the spindle in a tool change clocking

your thoughts?

jh

[SCzEngrgGroup]

John,

The CUI AMT 102/103 capacitive quadrature encoders are excellent, and cheap (under $30), with selectable resolution from 48 to 2048 CPR. At any reasonable resolution for this application, they are good for 15K RPM.

http://www.cui.com/product/resource/amt10-v.pdf

Typically available from stock at Digikey.

Regards,
Ray L.

[johnh]

That looks perfect SCzEngrgGroup,

through hole also! I assume I'll need some kind of signal processing card prior to the VFD????

In over my head on the electrical stuff, my main focus was the mechanical design at AAI though I will be able to tap the in house guru when it comes time to wire it up and make it work thankfully.

jh

[SCzEngrgGroup]

That looks perfect SCzEngrgGroup,

through hole also! I assume I'll need some kind of signal processing card prior to the VFD????

In over my head on the electrical stuff, my main focus was the mechanical design at AAI though I will be able to tap the in house guru when it comes time to wire it up and make it work thankfully.

jh

Depends on the VFD. Some will deal with a quadrature encoder, others just want to see a pulse. If yours just wants a pulse, just give it one channel of the encoder, or the index if you only need one pulse/rev (not all models have the index output, so be careful what you buy). Make sure they are electrically compatible. These are 5V encoders, and should have a pullup on the outputs.

Regards,
Ray L.

[johnh]

From all my reading it seams that as long as the taper remains dry and the pull force high, the friction alone should be more than enough to prevent slip under torque? It would be nice not to have to clock the spindle for tool changes later, but if I can do it why not right? I'm not sure if this VFD has a parking feature, it does have a jog feature so maybe that is what will do the job?

jh

[SCzEngrgGroup]

From all my reading it seams that as long as the taper remains dry and the pull force high, the friction alone should be more than enough to prevent slip under torque? It would be nice not to have to clock the spindle for tool changes later, but if I can do it why not right? I'm not sure if this VFD has a parking feature, it does have a jog feature so maybe that is what will do the job?

jh

The taper will do wonders, but at 5HP, depending on it alone may be pushing your luck, especially with a Belleville drawbar. I don't think clocking the spindle should be a big deal. I do it on the electric power drawbar I sell for the Novakon machines, and don't even use an encoder.

Regards,
Ray L.

[philbur]

The issue is the applied torque not the horse power and with a VFD you don't have anywhere near the same level of torque available as with a geared head. You can approximate the limit if you are so inclined, do a search on "cone clutch"

Phil

[ericnary]

Sorry for the slightly more 'standard' direction here but this is appears to have the best techies for this question:
Regarding the pcnc1100 series 3 with the emerson control techniques sensorless vector tech with fold-back logic
per a note on tormach site: 1.5 hp Brushless AC 3-phase Induction Motor

1100W continuous, 2800W peak (1.48hp continuous 3.75hp peek)
per an emerson article at the time they upgraded the drive to series 3 design:
per emerson article
Drive power capability was extended from 1.5 hp (5A continuous and 7A peak) to 2 hp. While the original drive had 150% overload capacity, the Commander SK provides the system with 230% overload capacity for outstanding carry through during tough cutting conditions.

So given that why does no one use the machine at 3hp. it appears from these specifications if the duty cycle is not to high this would be fine.
Why does no one ever take gwizzard and use a 3HP setting. I have one so I am also guilty of not going for it. The 2HP continuous is a thermal non stop rating and the 3.75 would be the short duty cycle if I understand this?
Other thoughts on why i have this wrong.

[johnh]

I talked to a Tormach tech and he hadn't heard of the 2hp capability when i mentioned it to him. I installed one of the early drive upgrades and I had a program that was maxing the HP putting the spindle meter solidly in the yellow, as long as the cut was stable and continous it would grunt through the cut, but if the same cut was on a helix entry a harmonic would start and the fold back logic folded back to zero rpm!! ouch. Made Greg aware of it and they promptly recognized the programing error and shipped me out a new SUB stick to reprogram the drive.

I have to say their service has always been top notch!

My belt sprockets came in today and the VFD ! I also scored a great 8" axial fan for the motor to scrub off the heat in high torque low rpm mode. It lools liek the best compromise is going to be running the motor / spindle without a reduction. I theoretically could get a few hundred rpm up to 8k


JH

[mountaindew]

Updates, progress, pictures?
Looking for some good reading during morning coffee
md

[johnh]

Just collecting components right now and working on the design details. Being careful to make this reproducible down stream for others to do a 3 or 5 hp upgrade. VFD is in, going to really crowd the electrical cabinet and have to add additional cooling there,upgrading the computer. Easy concept, many details.
Also a very unique spindle design is in the mix which is also complicating things. I want people to have an upgrade path from the stock Tormach to something that is very versatile.

jh


Attachment 276174

Attachment 276176

[keen]

Interesting thread.

I have done a lot of heavy machining on my 1100's and find the power to rigidity is quite a good match for milling.

Here is a pic of a heavy machining in tool steel job I do - and I have found with the spindle upgrade and load meter so you can watch motor load and optimise the cutter and cuts, machine rigidity is actually the limiting factor.

If you are drilling with big drills and spindle torque is the issue, then you have a good point. But if it is a milling metal removable upgrade you want - buy a bigger cnc.

Keen.