upgrading to pk299

[fozzyber]

I have just ordered pk299 4.5 motors to add to my 3.2:1 belt drive gear boxes.
we shall see how well they work in a few days.....
Mike you watching this......

[german]

Jerry, I'm watching you on that one (very interested)

[fozzyber]

OMG I built a monster!!!!!
Jogging at 17.5 ips, before only 6ips
I think I'm limited by pulse train as the motors would stall at 18ips on the table.
(remember 3.2:1 gear boxes)
I need to play with my ramp settings to dial her in.
One thing before with the old motors anything below 2ips sounded rough.
now pure silk at 1/2 ips.
BIG SMILE ON FACE today

[gc3]

aahhh...photos please

[german]

Jerry, I like that,
Now I'm thinking seriously in doing that with my PRS Standar; specially to take care of that sound on the motors when you jog at low speeds.
If you do not mind the bother I will be asking you frequently about your upgrades.

Thanks!

[fozzyber]

Sure, but have you done gear boxes yet, or that in the plans?

Also I have the 4g upgrade control box, need that to run the new motors.

With the new motors and gear boxes, the frame is looking like the weak link.

[fozzyber]

So far these are the upgrades I made in order.
1, control box 4g geckos
2, 3.2:1 belt drive gear boxes
3, watercooled 2.2 kW spindle
4, pk299 4.5 motors

Thanks to Stan H and Mike R for all their help

[gc3]

"With the new motors and gear boxes, the frame is looking like the weak link."

...and years ago the, I dare not say it, the "MM" was born

you have embarked on an endless journey of upgrades, tweaks and mods...

[fozzyber]

you have embarked on an endless journey of upgrades, tweaks and mods...



I thought that was the point......
If it is worth doing, it is worth over doing......:rolleyes:

[Brady Watson]

I thought that was the point......
If it is worth doing, it is worth over doing......:rolleyes:

Ha-HA! I love it!

-B

[richards]

There's nothing quite so satisfying as seeing an old machine learn new tricks. Congratulations Jerry.

Jogging at 17 ips with 3.2:1 reduction is impressive. At that speed you're sending 23,000 to 28,000 pulses per second, depending on whether you're using 30 tooth or 25 tooth pinion gears. That's about max, depending on which microprocessor you have on the driver board and whether you're using serial or USB to interface to the driver board.

[fozzyber]

20 tooth gears, SB latest BoB via USB @76% transmission, in a bot rod board, 201x geckos
That gives me an idea of maybe moving to 25 tooth gears. but I like the resolution I currently have.
do bigger teeth really downgrade resolution?

[Gary Campbell]

Jerry...
Switching from 20 tooth to 25 tooth pinions will:
Lower resolution by 25%
Increase speed (at the same pulse rate) by 25%
Decrease torque by, you guessed it, 25%
Depending on the mass of the axes and torque of the motors, reduce acceleration available

Looks like you get to "pick your poison"

[richards]

With the 3.2:1 reduction you have, you'll be safe with 25-tooth pinion gears. The math shows that you'll have 0.0006" per step resolution. (1.25 inch pitch diameter X PI / 3.2 gear ratio / 2,000 steps per revolution = 0.0006136 inch)

A piece of common copy paper is about 0.003". With 25-tooth pinions, it would take about 5 steps to move the distance of the thickness of a piece of copy paper. Because of the way machines are constructed and because of the tolerance that a machine must have to move without binding up, I doubt that you would ever be able to repeat movement that small.

A simple test is to buy two dial or digital indicators, clamp them on your shopbot about one foot apart and then move the carriage forward and backward repeatedly. That test will show you the "tolerance" built into the machine. Careful maintenance can reduce that "tolerance", but even with the most careful maintenance, you'll still see some deviation.