Surface Finish Issues On 12x36 (long Post) + Kb Electronics Vfd Install

This type of surface finish issue has been discussed in a number of posts, not uncommon with the G4003G and 1236 machines with single phase motors. Sometimes they are solved other times not. If everything else is tight, spindle bearings are set correctly, then the most common source of the problem is belt tension/alignment/matching, and issues surrounding the single phase motor and isolating it from the machine. You have done a very thorough job on the belt concern, checking the usual culprits. Although a lot of people favor the linked belts, there have been some tests on vibration/smoothness of cut and a good cogged belt was found to work the best overall. I like the Gate Tri-Power, but any decent belt should work. The stock belts on most of these machines should get tossed up front. Most of these were pointed out previously: http://www.hobby-machinist.com/threads/lovejoy-coupling-for-lathe.38870/

The insert you are using, tool post, etc. all look good and should work well. You might put you hand on the side of the tool post and see if there is any flex or chatter, also check the gibs, or try to lock the tool post and cross slide and see if there is any difference. Make sure the insert is well seated, and there is no tooling flex. Next step would be to try to do some form of motor isolation, some discussion in the second link below. It could be a balance issue in the motor or just the cogging of the single phase. Three phase gives a much better finish, but I would not want to do the investment and find out it didn't fix the problem, but 3 phase with a VFD have a lot of other upsides. I do recall an issue with the spindle bearing tension causing vibration, and readjusting it helped. But I would go there as a last resort.

Last but not least, if you haven't already dons so, you might look into different feet, improving the rigidity of the bases, and or mass loading the bases with some sand in bags. Check the lathe leveling and the feet are similarly loaded.

If you are seeing the same type of cutting pattern in different metals and with different tooling holders, then very unlikely to be the insert. If you only have one insert holder, you might try another type/design, I like the CCMT/CCGT types as my main insert.

http://www.hobby-machinist.com/threads/grizzly-g4003g-belt-vibration-video.22308/
http://www.hobby-machinist.com/threads/g4003g-motor-vibration-surface-finish-issues-fixed.42604/
 
Mark, thanks for the response. I was in the process of sending you a PM to see if you have any info available about 3 phase & VFD on the 1236. I "fat fingered" something, & lost it.

Anyway, I already have a new Leeson motor and a KBDA29 drive. I have connected them on the bench and so far, all is well--no magic blue smoke.
Tomorrow, I will pick up the add on IODA board for the drive. It allows for remote switching & speed controlling. I have manuals, but the knowledge to use them is somewhat lacking.

I followed your post about using mostly stock parts on the 1340, and that is the route I desire to pursue, also. No need for light power or coolant power, either.

If you have the time and inclination, maybe we can work something out so that I can proceed. PM??

Thanks,
Jerry in Delaware
 
Again, if your are cutting Aluminum with carbide, you will get a much better finish if you speed it up. 7/8" or 1" diameter part at 1400 rpm should cut better than 720 rpm.
 
Hi Jerry,
Let us know if you have the same cutting pattern issues when turning other materials, I often use 600-800 RPM on 3/4-1" aluminum, and have not had any issues with the finish cut, but for real nice finishes I use very sharp positive rake uncoated carbide inserts (like CCGT) and can get close to a mirror finish.

I started to put together a suggested parameter change worksheet for you, and then ran into the issue that this VFD states an "IODA Option Board required" to run any of the commands by external inputs. I see that you are going to pick this up. I had KB VFDs in the past, but switched to full function VFDs because of the additional costs when you start adding all their modules. Still, it should work fine in this application.

With the IODA module, you would use a 5K pot for speed control, using the voltage sources which is the default jumpers on the board. Connections are per page 52 in the manual. I would use inputs 1, 2 and 3 for Forward Reverse and Multispeed 5Hz for Jog. I have attached my recommendations on the parameter files.

You could use the stock For/Rev contactors (after disconnecting all the HV wires to them) to switch the VFD signals and wire the jog as a separate contact to the I/O board. The PM1236 comes with coolant/light so you would need to put that on a separate circuit/controls if run through the contactors. You could use the stock system breaker or fuses to provide power to the VFD, motor connections would be direct connect to the VFD. Also note that I have not had much success with using used contactors switching low level signals. The contact resistance tends to be too high because of the burnt contacts. But you can give it a try. The contactors could be replaced with relays. You would not need the thermal oveload for the motor. I have built completer systems for the PM1236, it was a bit more challenging and time consuming than usual. You also need to wire in all the safety interlocks.

Going to 3 phase should help a lot, and the Leeson motors have been very good in this application. You can pm me if you have questions,.

Other threads worth reviewing:
http://www.hobby-machinist.com/threads/pm-1236-vfd-conversion.11649/
http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=96363
PM1236 VFD Control System.jpg
 

Attachments

  • KBDA VFD PROGRAMING PARAMETERS WITH EXTERNAL CONTROLS.pdf
    453.3 KB · Views: 101
  • KBDA-29 MANUAL 1.pdf
    1.6 MB · Views: 89
Last edited:
Thanks Mark for the reply. I just got in from picking up the IODA board and taking the wife shopping. I have not had a chance, yet, to study your procedures.
I noticed that the KB drives were significantly more expensive, also. I had already ordered the 29 drive from EBAY before learning that the IODA board was extra (live & learn). It was new old stock, & I got it for $249. The IODA was $75 at ELECTRIC MOTOR WHOLESALE here in Delaware (about a 40 minute drive from where I live). (http://www.electricmotorwholesale.com/)
I am not affiliated with them in any manner; but, can truthfully state that they are fantastic to deal with. Their facility is actually a large (barn-like) structure way out in the country. I have dealt with 4-5 of the employees and cannot say anything negative about them. Then, and this is a biggie, their price on the Leeson motor (in stock) was about $50 less than any other vendor I found on the web. The IODA board (in stock) was $75. So I am into an American made drive for about $325. It appears that a large portion of their merchandise is drop shipped from the manufacturer or other location. Also, Delaware has no sales tax to contend with. Anyway, if I can get it all together It should be a very good system.

Thanks again for all the info.

Jerry in Delaware
 
Good idea, Tim; however, I think that I will look into that after I get the other mess taken care of. My reasoning is to only try one or two things at a time so as to be able to identify where the problem actually lies. That is one of the reasons behind not upping the RPM as you had earlier suggested. If I change too many things at once, I'll probably not know what (if anything) fixed the problem.

Another thing that I finished up today on the lathe. There are 4 bolts for holding the headstock to the base cabinet. There is no way on Earth, or any other planet, to install the furnished bolt (the one closest to where the lead screw & feed rod come out). These bolts are the metric version of 1/2 inch (maybe they are 1/2--but it doesn't matter--STILL WON'T GO IN!!!). These bolts thread into strap steel bars welded to the top of the cabinet. The one described will simply not go into the hole let alone getting the threads started. My solution is a 3/8 grade 5 bolt with washers inserted from below. The clearance is so tight that a 3/8 nut sitting on top of a flat washer will not fit either---AHHHH!!!!--I have a nut thinner (lathe). So I turned about 3/32 off of a nut & now I have 4 bolts holding the HS to the cabinet.

Mark, I thoroughly read (& re-read) your info. I have already reset the programming on the VFD (still on the bench with the motor & IODA board connected).
I have the schematic that Ray C. posted, also. I will be attempting to follow that--using your info where applicable.

I have not attempted to check the switches (contactors) for fwd/rev yet. I have been experiencing a small, but irritating, oil leak on the front of the HS since I changed the oil. So I tore into that. Since I needed (or thought I needed) to remove the face plates to access the switches & sundries, I figured it was a good time to locate & hopefully repair the oil leak. It turns out is was around the gasket on top of the HS. The gasket was in good shape, so a good cleaning & a layer of Blue RTV, & I'm just idling while I give the RTV some time to cure prior to snugging it down.

Back to the project, now. What would you recommend for wire (gauge??) to run to the IODA?? I was thinking telephone wire, but have not a clue. I liked the phone wire idea since it is solid, contained (sheathed), easy to identify, and readily available to me. Ideas, opinions, recommendations???

One thing I forgot to mention yesterday about the VFD--It came with the waterproof connectors, and the on/off switch which total to about another $5o if purchased separately. All in all, unless something catastrophic occurs I don't feel too bad about this purchase.

Thanks to all for the ideas.
Jerry in Delaware
 
I have this problem on my South Bend 13. Why? It's not the motor, although it is single phase. It's because of inconsistent carriage speed causing a constant frequency in toolpost deflection. Basically, the tool post nods in and out. This is caused from the heavy carriage/bed wear in my lathe, and now the pinion that moves the carriage is spaced out from the rack, causing a bumpy motion. My advise for you is to remove the rack gear under your bed, and shim it downwards slightly. This might help.

Sent from my XT1053 using Tapatalk
 
Do not use solid wire for the connections, it will fatigue and fail over time. I use standard 18-22G wire in the control box for low voltage connections and use crimp pins for the VFD end, spades for other ends. I tend to use 18-24G stranded shielded cables, the drain wire is attached at the VFD end only. This would be for VFD level signals. It all depends on how you wire everything up. I often use flexible Beldin shielded cable, something like this:
http://www.ebay.com/itm/25-Belden-9...-Low-Capacitance-Cable-9C-24AWG-/262239125129
http://www.ebay.com/itm/24-9-24-gau...Quabbin-8195R-Belden-9539-50-Ft-/322007638873

I use shielded cable between the VFD output and the motor connections because of the electrical noise generated, shield is connected at the VFD, ground wire at both ends. So something like 14/4 shielded. But it is hard to source VFD specific cable, and it needs to be a minimum of 600V rating.
Example would be http://www.ebay.com/itm/Alpha-Wire-...ielded-Cable-Robot-Comp-25-roll-/232019607914
 
I will just throw this out as a possible cause. Toolpost mounted in a nut that is too high or very close to compound surface and then a chip getting caught between and post not sitting perfectly flat. I have had this problem and took for ever to figure it out. A toolpost rocking on top of a chip will leave a poor finish, with a hammered look to it. Not to be rude or insult your experience but could it be your tool is a few thou above center, I would look for the simple, easily overlooked issue.

cheers
michael
 
You must log in or register to reply here.
Back
Top