Thanks Jim,Quote:
Originally Posted by Jim Dawson
That looks like the place to buy for me. Close to home and no shipping!
Ray
Thanks Jim,Quote:
Originally Posted by Jim Dawson
That looks like the place to buy for me. Close to home and no shipping!
Ray
It's actually quite a common practice, being a lathe 3hp would be good for your R8 spindle size, the mag clutch should work well you want to plan a disc brake as well to lock/ hold the spindle position when milling and drill Etc.Quote:
Originally Posted by allaces
When looking for a motor look for inverter duty these a built for VFD Drive use and last a whole lot longer than a regular AC 3 Ph motor, they are out there and at good prices sometimes
Not all of them only some models have the 6,000 RPM rating washdown motors mostly and they can go more I have run them over 8,000 RPM without any problemsQuote:
Originally Posted by Jim Dawson
I got more questions for you!Quote:
Originally Posted by mactec54
I'm looking at incorporating a brake as you suggested...
I'm thinking that a "second mag clutch" would do it... they are CHEAP and easy to modify for my need.
https://www.ebay.com/itm/AC-A-C-Comp...1/223097334901
Plus they are both 12 volt (which I'd be already using) and could easily made to engage at the end of each index with 10 HP of resistance. Talk about overkill! No need for hydraulics or other mechanical actuators of any type.
Would this motor be a good choice?
https://www.ebay.com/itm/CEM-Rolled-...e/323289273721
You indicated 3HP... so am I wasting my time looking at 2HP?
In your opinion... what is the lowest RPM that a 3HP 3600 RPM motor could run at and still produce enough useful torque when geared or setup to run at 5,000 RPM?
2" diameter steel shafts are probably the largest diameter I'd be machining on this machine.
Would a 3HP 3600 RPM motor be capable and reasonable to machine that considering that my setup would be basically direct drive?
If I don't buy a new motor... what should I look for on a nameplate to indicate that it is "inverter duty"?
Generally speaking... do you think I could efficiently run the average VFD controlled 3600 RPM motor at 5000 RPM.... or would gearing it up be better?
I'll be using gears anyway, so which way would give the best end performance?
It's my feeling that I will loose valuable torque either way.
This is off topic... but I should probably elaborate a little on the R8 spindle I mentioned in the thread.
The spindle is actually going to have a #5MT nose like my converted lathe has "without" the D1-4 section. This gives me a decent "hole thru spindle" for the size of lathe I'm designing. I may add a thread on the spindle nose for custom drive plates, etc... and the following sleeves allow me to use all the collet types I have and more...
I already use the following sleeves on my converted lathe, and these sleeves will easily handle the 5000 RPM on my new one.
#5MT to R8 (this one is an addition and I need to make it) Can't find a store bought one...
#5MT to ER40
#5MT to 5C
##5MT to 4" 3 Jaw
#5MT to 4" 4 jaw
... all of which I already have the tooling for, and thus provide me with lots of versatility for the type of work I want/need/do.
And... I could easily make custom #5MT to ??? for any other needs I may have.
The reason for making my own CNC is mainly for the speed and accuracy to machine smaller parts. My Manual lathe (which I converted), can still operate in Manual and/or in CNC mode, but it can only handle 2000 RPM max. Plus... by making my own CNC, I can avoid all the complex mechanical problems/issues associated with a manual machine conversion. Conversions are "not clean" and "usually compromised". For me... it's now "much easier" to build a dedicated CNC from scratch for my needs. That may not be the case for most hobbyists because you need some prior equipment, or access to some to accomplish that.
and MOSTLY...
I'm not able to find what I want or need in a CNC without giving up my legs and possibly my arms... then what would I do?:)
Ray
After thinking about it more... I think it probably would be better for me to run the motor with a step belt and pulley system "outside" the spindle head to get low range torque for machining larger diameters. I'm thinking of a 2:1 ratio. I would therefore not need a huge motor and it would not affect the indexing ability I was looking for. The motor driven step belt pulley system could then drive the indexing geared shaft to the spindle inside the head. With this in mind do you think 2HP would be adequate?Quote:
Originally Posted by allaces
Ray
The step pulleys will work fine. I'm having a bit of trouble getting my head around what you are saying about the geared indexing shaft.
I'm looking at the spindle to only have the driven gear, position/speed sensor, and bearings on it.Quote:
Originally Posted by Jim Dawson
Next to it will be what I'll call the driving gear/index shaft for this spindle.
One end of this shaft will have the 2 clutches and Nema 34 connected to it for indexing.
The other end of that shaft will be the driving gear, support bearing, and external driving step pulleys I mentioned.
- I'm revising this above idea to using a timing belt instead of gears inside the head. Now days... you can get pretty rigid setups using them with pretty much 0 backlash. I already use that setup on my converted to CNC mill/drill, to operate a second spindle. Adjusting and maintaining C/D is also easier, plus no oil lubrication required.
- I'm also looking at putting the "brake" using a mag clutch on the spindle shaft instead of the driving gear/index shaft I mentioned above. This would eliminate milling force vibrations created from the connection between 2 shafts. I ordered a few mag clutches... I'll see if can somehow fit one on the 2" diameter spindle shaft... I doubt I will be able to... then a disk brake may be the best way to go.
Again... this is still work in progress, so learning and changing my mind is part of the process:)
Any suggestions are greatly appreciated.
Ray
For an example check you Haas with the Rigid Tapping and the spindle orientation, these are using a regular inverter duty Baldor motor the encoder is on the spindle, they use a lot of DC to control the stiffness of the motor to a point of locking the motor, which you can do with some regular VFD Drives does not have to be a vector drive I did it with this Bridgeport Boss5 standard Ac motor and Yaskawa VFD Drive Encoder on the spindle and a brake on the spindleQuote:
Originally Posted by Jim Dawson
The control also plays a big part as well
Very nice and clean looking setup.Quote:
Originally Posted by mactec54
How is the disk brake sequentially operated?
Ray
Would you happen to know what the field coil bore diameter for this clutch is, it more than 2"?
https://www.ebay.com/itm/AC-A-C-Comp...1/223097334901
I can't seem to get an answer from anyone for that..
If it's over 2" then that could possibly allow me to use it for a spindle position brake right on my main spindle.
Ray
I’m running a 2hp 3500rpm Techtop with a 3hp vector drive and have run it at 7000rpm and I’ve turned diameter of 8” without any issues however large diameters you’re turning slow anyways it’s just too much swinging around. For 2-3” diameter I maybe turn at 4-5k range. I was going to upgrade to 3hp until I switched to a vector drive now I’m not sure that’s even necessary. It practically polished as it cuts at high speeds and no issues grunting through cuts 2mm deep in 7075.Quote:
Originally Posted by allaces