View Full Version : X Motor

02-09-2004, 10:53 AM
I have a question regarding my x motor sounding as if it wants to run with a hum but will not turn, after switching the drive motors and cables it works fine. The problem is with the out-put from the board. What do I do? This was caused when the rack bound an the stop bolt. Any help is appreciated

03-05-2005, 07:17 PM
I have recently found a problem that I could use some help with. I have a PRT 120/60 but only have a 96/48 bed on it at this time. I cut a piece of 3/16 polycarbonate that was 48 x 48 and I cut 46 5/8 x 46 7/8 from it. It turned out 3/16 out of square. I immediately set about squaring my gantry and checked it with an "A-Square" (3' x 4' x 5' has a perfect 90 degree corner on it.

Now I start cutting doors with doorbot and find that they are out of square. Just for curiosity sake I released the tension spring on the inboard X motor and moved it down out of the rack and that end of the gantry moved to the left approx. 1/4 inch. I re-engaged the motor, moved (jogged) it back and forth then repeated pulling the motor down and got the same results. Anyone have any ideas?

03-05-2005, 07:34 PM

Ther are two ways to solve your problem. One would be to make the nessacary adjustments to your Y carrige so that is closer to square when you turn on power to the motors. The second way is to make sure you are square when you fire up the system. To do this the first thing you need to do is square your Y car to the X axis. Then set your stop blocks agains't the square Y car. Now every time you apply power to the system hold the Y car against the squared stop blocks. I learened this from Ted at the Camp in NJ. Once you do this you will be cutting square parts.

03-06-2005, 09:24 AM
A question along the same lines:

Has anyone had to adjust the position of their "stop bolts"?
I have a factory built PRT96 Table and my full range of motion in the X direction is 95.5".


Brady Watson
03-06-2005, 09:41 AM
If you have a PRT96, your rails are 10' long & the X carriage is 22" wide. You should have a range of 98" from -X limit to +X limit.


03-06-2005, 12:05 PM
On our PRT96 we have changed the stops so that the rollers get within 0.5" of falling off the rails. Our total range of x-travel is 2600mm (or slightly more than 100")

For squaring the gantry, we have put adjustment screws into the stops. See this thread (http://www.talkshopbot.com/forum/messages/26/558.html) - the pics there show the wheels getting near to the end of the rails.

03-06-2005, 12:14 PM
Is there any danger of the cog disengaging with the rack at this distance?
He who wonders if they are still sending freight from America to Europe by sailing ship

03-06-2005, 12:25 PM
I am sure that we looked underneath to see if the "cog"(pinion) wanted to disengage - but maybe we overlooked that?? However, we do manage to hit the stops pretty hard, so I reckon the pinion and rack are still fully engaged.

I couldn't care about your ship, I want to see photos of your table!

03-06-2005, 12:50 PM

03-06-2005, 01:20 PM

03-06-2005, 01:33 PM
I'm confused. I remember from the ShopBot specs that the X travel should be 102", so that when mounting dual routers/spindles, both tools will have the ability to reach the full extent of a 96" workpiece.

My x travel is 102.1". The table was assembled by ShopBot and I have not modified anything that would affect the travel of either axis.

From the ShopBot web site, specs for a PRTAlpha 96:

"Nominal Cutting Area: 96" x 48" x 6"
Actual Full Cutting Area*: 102" x 50" x 6"

*Actual full cutting area is the area that can be covered using one z-axis. If two z-axes are in use, both will cover slightly more than the nominal cutting area."

My understanding is that this was the case before the Alpha's were introduced as well.

Brady Watson
03-06-2005, 02:05 PM
You are correct.

Hey Mike...Nice massage table!


03-06-2005, 02:32 PM
Hi Mike,

sorry this is off topic.

You'll be pleased to know that mine came via Pakistan Airlines.....

03-06-2005, 02:44 PM
I think Orville and Wilbur Wright may have mine?

03-06-2005, 03:19 PM
To Clarify (I think):
My X Rails are 10 feet long.
If I remove the stop bolts that are located approx 12inches in from each end of each X rail, then I can move further than 95.5 inches.
I purchased the PRT96 second hand, however I know that the table was made by Shopbot (sometime near the end of 2000)
I noticed that the limiting bolt that is on the Y carriage (that hits the X axis Stop Bolts) doesn't line up directly with the center of the of the Y Carriage (in the X direction), consequently , the 95.5 inch cutting area of my machine is not centered between the 10'. It is offset in one direction.
As I am not near my shop right now, I am just assuming that my stop bolts on X Rails are +/- 96" apart and the 1/2" that I am missing is due to the 1/2" width of the stop bolts.

I was considering drilling new holes for my stop bolts to give myself a few extra inches, however first wanted to see if I was perhaps overlooking something.


Brady Watson
03-06-2005, 04:33 PM
The stop bolts were not pre-drilled on PRTs...and since this was left up to the user, chances are that they were not drilled in the proper location by the original owner. Read the assembly manual and drill new holes...that should fix your problem.


03-06-2005, 08:33 PM
Thanks for the info.
I will drill new holes.