Work To Do On My Bot...Tricks and Tips Please!

[rb99]

So I have a pr with a very heavy steel table with a cutting area of 5.5' x 12'.

I bought:
new 4g controller (new and installed)
new 12" retro Z with round router clamp (arrived)
new 3.6 motor for Z from OM (not arrived yet)
new 25 tooth pinions for X & Y, and 20 tooth for Z (not arrived yet)
75' used e chain (arrived)
Kent dust shoe (arrived)

When the parts arrive I will install the retro Z, motor & pinion. I may keep the ball screw Z and have the 2 Z's if there is room.

I will change the 7.2 motors on the X & Y to a set of 3.6 motors I have, and put on the new pinions.

Put on the Kent shoe and hook up the collection hose, including grounding.

Make a new zero plate with a hole to allow for X Y and Z zeroing.

Make some type of carrier tray for X and Y e chain. I have enough to have e chain completely cover the X and Y runs.

Then I am ready!

Phase 2 will be bringing a dedicated electrical panel into the garage. That will give me access to 220V power single phase. I will build the black box to hold 4 Lighthouse vacuums and plumb & cut a vacuum hold down. I can possibly hook up my 5hp Colombo spindle as well.

Any advice? Tips? Especially with the Z...

[gc3]

a cheap but very effective upgrade for the rails...put 1/8" angle iron on the unistrut...

[Brady Watson]

Nice one, Gene.

Motors...If I can make a suggestion/recommendation:

You might want to keep whatever 7.2s you have on the machine for better resolution and torque. Also, ALL PRTs equipped with a Colombo 5hp came from the factory with a 7.2:1 motor on the Z. It's just too hard on the 3.6 motor to move that beast up & down. Tools with a Porter Cable et al came with 3.6:1 on the Z because it is much lighter. (I think you mentioned a 5hp spindle in another thread?) Plus, you'll get 2X the resolution if you get into intricate 3D designs that need it.

If you are worried about speed with the 7.2s, don't be. As long as you have really good communication efficiency, then you should have no problem running that tool at least 6 if not 8 IPS. I have not tested these speeds on an SB, but with Mach and I have reliably jogged the tool 1200 IPM with Geckos, 70v PS and 7.2 Orientals @ 45khz. The SB controller with good COM can do at least that. The additional resolution and torque you'd gain are well worth any loss of speed you might have on the top end. Since you are running 'open loop' - non-Alpha, you want all the torque you can get. Plus, most cutting is typically done 4 IPS or less anyway.

Something to ponder...and test/try if you've got the motors on hand anyway.

-B

[rb99]

Brady what pinions do you recommend? It is too bad... after I bought a new 3.6 for the Z, and all new pinions...The 3.6 change was a SB tech support recommendation.

Gene I had done that 12 years ago, but SB flew in to help troubleshoot poor cutting issues and promptly removed them. I think the issues I had back then were the original controller. Then they came out with the PRT...

What speeds can you run at and what motor/pinion combination do you have?

Edit: It would be easy to add the Bishop Wise rail to the top of the angle and change the angle of the wheel to 90 degrees. Then add a spring loaded hold down for the bottom wheel.

[Brady Watson]

You can run 25s or 30s with the 7.2s - not 100% on what is available right now since you have 3/8" rack. If you bump up to 1/2" rack, you'll have more choices.

You can run the angle like Gene shows, 3/16" flat bar, 3/16" angle with L pointed up (you'll have to grind your own in that case) or use the BWC rail and spring load it. I think Ed Coleman did this to his PR.

Yep...here ya go: http://www.colemanwoodworking.com/sb_rails.html

-B

[gc3]

4g board, 3.6 motors with 25t pinions. xy jog 12ips cut 4-6ips

[rb99]

4g board, 3.6 motors with 25t pinions. xy jog 12ips cut 4-6ips

Do you think you would benefit from the 7.2 resolution Brady mentioned?

[Brady Watson]

Do you think you would benefit from the 7.2 resolution Brady mentioned?

It depends on what you plan on doing with the tool. Personally on an open loop tool, I like the 7.2s because you can get into some really intricate/small reliefs etc.

-B

[rb99]

It depends on what you plan on doing with the tool. Personally on an open loop tool, I like the 7.2s because you can get into some really intricate/small reliefs etc.

-B

With the built in gearbox backlash and no backlash compensation in the software does it really make any difference?

[Brady Watson]

Yes it does - if you have the SB TH version of the gearbox, they are tighter than the SGs. The SGs are a little sloppier, but 2X the torque is worth the swap alone in my opinion. There comes a point where the slop in the chassis, gantry, old worn rack and other factors all stack up - so the little bit of backlash that one motor has over another kind of becomes a moot point.

Worst case - try it for yourself and make your own decision.

-B

[rb99]

Yes it does - if you have the SB TH version of the gearbox, they are tighter than the SGs. The SGs are a little sloppier, but 2X the torque is worth the swap alone in my opinion. There comes a point where the slop in the chassis, gantry, old worn rack and other factors all stack up - so the little bit of backlash that one motor has over another kind of becomes a moot point.

Worst case - try it for yourself and make your own decision.

-B

Neither of my motor sets are TH...

[Brady Watson]

Try each set of motors for yourself - YOU be the judge. That's the only way to find out for sure.

-B

[rb99]

Now I feel bad for buying a brand new 3.6... and it has not arrived yet.