Gerald D,
I have myself is a self induced problem. I purchased laser cut parts and now I managed to lose only one. Herein lies my problem. When I joined the forum, the pdf prints were free but the dxf were not available, I know because I asked. I know the prints are available for a charge but I already have the pdfs. Not long after I elected to purchase the laser cut parts because it was cheaper than having the old company I worked for to cut and form them because it would of require a setup and processing charge. When you made the pdf of the drawings was it a print conversion from the drawing program that you were using. The reason I am asking is I can convert the pdf to dxf and scale it to the dimension on the pdf. This will only be accurate if the pdf was generated from the drawing program and not from an image. This way I can have it made on the cnc mill where I work.

What part do you need? I can hook you up.

M1 30 332

Ok, I converted and scaled the drawing. Ran it off on a cnc mill. Fits good as far as I can tell.

OK - well if you still need the part I have one I can send you.

Thanks Mike, the offer is greatly appreciated

Here is a tip for anyone mounting the rack on the x and y. I have used probably every double sided tape that 3m makes and they make some good high quality stuff but if you want to save money and have a very high bond, here is a tip that a hvac tech told me when we were installing duct board. Apply an even coat of an heavy duty spray adhesive (ie 3m Super 77, Misty, Sure Stick) and apply your tape. This works with Nashua tape as well as double sided tape. In this case I cleaned and prepped the metal to ensure good contact surface. Using a clean flux brush apply adhesive (spray adhesive on bristles of brush, not directly on steel, the over-spray is horrible to remove) to the back of the rack. Let set one minute and apply permanent foam double sided tape. Brush adhesive on the rail. Now here is the tricky part, you will only have seconds to position the rack. Once the two adhesives make contact you have better be close. To give you an idea, directly after I had my rack applied and positioned, I could pick up the entire rail by the rack before I put the fasteners in. I did not do this on the one side and I can tell you that the rack can be peeled back of with not much trouble, if you use spray adhesive, you can separate the two but you will have to do prep to remove the foam that ripped in half.

I would advise against foamed double sided tape...
Not only I have very bad experience of them falling apart as they turn brittle overtime.
If I remember correctly, Gerald did advise against certain type of foamed double sided tape.

It all depends on the type and brand. I am using the same model of 3m that we use at work that we order from mcmaster carr. It is a permanent foam for metal applications. We use it all the machines there and it generally removes removes the paint from the machines when it is removed. Most of them are exposed to coolant and oils. I do agree that you can purchase a lesser quality foam tape but you do not need automotive grade tape either for the application.

Question on 10 60 315 and 10 60 325?

Should not the height of the mounting plate be extended to match the loop height to match the post by Gerald in thread http://www.mechmate.com/forums/showthread.php?t=498
The loop height is 9.25 inches and if you mount it on top of the 10 60 325 the placement of the bolt holes is at the bottom radius of the 2x4 tubing. So wouldn't it be better to to extend the mounting height of 10 60 315 or place an offset in 10 60 325? This would add an additional bend process and recalculation of the blank length for that part.
I am using the Igus McMaster Carr 4516T22

You don't want 315 to be mounted too low on the gantry because it will protrude too much into your workspace under your gantry.

325 can simply be creased to tip its nose up at an angle, and that lifts the first link of the e-chain quite a lot.

Gerald,
I noticed on 10 00 000 that it shows an offset in 10 60 325 but the profile does not have that. Since I elected to use the Igus with the 9.5 loop height I will have to raise up the 10 60 315 1" with cylindrical columns and longer bolts. This way the track will not be lower than the gantry tubing. I only thought it was interesting it was shown in one area but not the other and would be most consistant when looking at the drawings. Maybe only a note would be needed on the drawing to adjust the blank length for 10 60 315 to match the offset that would be needed for the cable chain you select.

Do you understand what I meant by "creased to tip its nose up at an angle"?

Sorry for the wait in reply, I just got off work. No Sir, I do not follow your meaning of your post.

Gerald, do you mean to bend the mounting area for the chain up to create a different angle of mount to raise the chain and increase the loop height?

Bend up at the red line

Gotcha and thank you

Electronics ordered (they were backordered), motors and power supply received. A little mechanical work left. Having router mount machined, still need gas spring but need to wait and see final assembled weight. Machined pinions tonight and motor mounts. Most likely paint prep the rest of the week.

Has anyone used nylon bolts for mounting the board surface? I was reading some of the fire stories and wondered "why not use nylon bolts?"

Hi Pete,

Have two new gas shocks I will sell they are Macmaster –carr
#9416K181 20 lb
and
#9416K361 15 lb
they are new and never used
$10 each
Had to go to 30 lb for my spindle,

Al drouin

Al,

Thanks for the offer but my spring also will be over 20lb. Most likely a 30 but not sure yet.

Motor Wiring?

I have the PK296A2A SG7.2 with the G203V with the PDMX-134 and the PDMX-126. First off, my head is spinning on the half coil and unipolar wiring. Do you mean that to wired half coil is only to use 1/2 of the coil? I am not sure I fully understand this and how the motor would every function. Please forgive the lack of understanding, I am used to induction motor wiring where you parallel or series the windings but all the windings are always used. Oriental motors tech support on the other hand says to Unipolar wire that all six wires are supposed to be used, however, in the posts I have read a lot of them say that unipolar is half coil and only 4 of the 6 wires are used. My head hurts.....

Also since all the calculations are based on unipolar the stated current set resistor is to be 35.25 for 3A which leaves the option of 33.2k, 34.8k or 35.7k resistors. I just feel like I am missing something here. Sure I could just follow the rest of the setups posted and not fully understand but I am interested in fully understanding the wiring and why the discrepancy in the wiring information I am reading.

The best answer is this I found at CNCZone. It explains full and half coil but then what is unipolar?

Picture might explain a bit more
http://www.probotix.com/cnc_images/unipolar_ill_02.jpg

as I understand 8 wire motors have 4 separate winding and it is possible to use only two of them as a complete motor and have other two in some kind of "reserve". it gives less torque just as unipolar winding which got its name from unipolar way of controlling the motors.
Look for thread "selecting motors for mechmate" you might find some more info about it.

Danilo,

I have read most of them already and I am very familiar with the diagram. However my confusion came into when I called Oriental Motor to verify the unipolar wiring, the tech insisted that all 6 wires must be used and the center tap is the common and the other two are tied to the respectable phases (a or b) depending on which coil you are working on.

This was from Unipolar, Bipolar series, Bipolar parallel, choices for 2phase steppers thread. It has also been stated that due to the fact that the SG7.2 gearboxes cannot handle any more torque than a half coil configuration anyway, using full coil and the higher voltage needed just wastes more heat. The half coil configuration due to the much lower inductance needs a lot lower voltage. Hope this helps a bit. :)

Finally painting, ready for wiring

looking good (but you seem to have strange apparitions floating around your garage :) )

Alan,
I think that might be the censors. :)

Perhaps the "ghost" in the machine.

I was trying to keep the focus on the machine and not the junk I have cluttered around.

Pete,

Sorry to be so late to respond.

The current limiting resistor is not critical. You can use any standard value close to 35K. I normally use 30K or 33K.

Look at the chart posted by Danilo on May 15th. The Unipolar chart shows the wires for your motors. The A coil has three wires, Black, Yellow and Green. The B coil has three wires, Red, White and Blue. When wiring the motor half-coil, for the A coil, you can use the Black/Yellow wires OR you can use the Yellow/Green wires. For the B coil, you can use the Red/White wires OR you can use the White/Blue wires.

Bipolar means that each coil has two poles. The stepper driver has eight transistors that switch the polarity of the windings. That's why you only use four of the wires.

(Oriental Motor's unipolar drivers use an entirely different scheme. I have a bunch of them sized to drive the PK268 size motors. Because the drivers are different, you just have to trust Gecko that they are doing the best thing possible to drive your motors - they are. I've run some significant tests between the G203v and the Oriental Motor unipolar driver for the PK268-02A motor. The Gecko drives the motor much faster and much harder.)

Wiring the motors half-coil will give you 70% of the motor's torque. Because the motor has a gearbox, 70% is MORE torque than the gearbox can handle, so you get maximum speed, snappy performance and enough torque by wiring the motor half-coil.

Use a 35VDC to 45VDC power supply that has at least 20,000 uF of capacitance (30,000 would be better). The harder the motors are working, the more current they pull. The more current they pull, the more they drain the capacitors between charges. Having large capacitors means that the motors will always see almost the full voltage all the time. Smaller capacitors means that the voltage will droop, which will affect the top speed.

Above all, don't sweat the electronics. A CNC machine is not a constant motion machine. The speeds vary. The load varies. More important, the density of wood varies and the sharpness of your tooling changes - while you are cutting. You'll probably find that setting your speed and depth to 50% or 75% of maximum will give you better over-all throughput than trying to run at 100%.

I learned that lesson the hard way with my Shopbot PRT-Alpha. I drove it at maximum speed and maximum depth, and learned that the "Alpha" feature worked because I had divots in the work when an axis bogged down and then recovered. When I slowed things down, by 25%, the machine never went into "Alpha" mode. The divots disappeared and I realized that I had wasted thousands of dollars buying a machine with the "Alpha" feature when the Shopbot software did not compensate for the speed variations of the motors.

Mike,
I think I have read every article on the web but your was the easiest to understand. I understood the wiring but did not understand the stepper and how it works. It is nice to fully understand every component. I have been reading about Mach3 and understanding the interface with the 126 breakout board. I am adding a second parallel port to handle the additional inputs. Have done a lot of reading to find one that works with Mach3. Been busy building a fort for the boys so I have not much time to post.

Some of my previous posts I had questions but never told the solutions that I used. I will be trying to post pictures of what I have done and progress.

I used C7 x 9.8 channel and the machine is all bolt together. The C channel had a U profile to it and I needed to level out the X rails. I mounted the x rails with M12 bolts for extra holding power to compensate for the bowing in the x rail from machining so much of the 2.5" side down to mount the v rail. This was only needed on the X and not the Y. The first pic shows the side view with the M5x0.8 set screw visible in front of the mounting bolt. The second is a top view. The third is a view the the v rail mounted the the angle iron, the pic is deceiving but the rail mounts on the rail on the vertical edge and does not set on any part of the radius.

nice job

Pete,
What was your reasoning in using the angle iron instead of the Aluminum channel for the prefab Vrail?

Heath, mostly price and availability. The aluminum would have been easier by far but the cost and lead time here was too high and too long.

Pete,
That is a nice solution to the "toe in" challenge that happens with some of the C channel available lately.

The "squaring" of the leg of that structural shape has been done a number of ways over the years.
Some of the solutions used that I can remember seeing here:
- Building the end gates of the assembly with adjustable tie-rod type adjustment to allow toeing in or out of the C channel to the top face gets in plane.
- using BONDO, (car body filler) on the top face, and sanded square
- shims used in the same place you put set screws to get the angle to set square.

Nice work.

Wiring and Mach setup almost complete
 

Have some minor wiring changes to do. Need to change the 8mm proximity home/limit switch for the Z axis to a 12mm. Seem to have some problem with the 8mm switch picking up interference when it is grounded (barrel of the proximity switch touching the steel). It does not do it with the 12mm switches though. All the steel is grounded by a connection wire and all wires are shielded. It is odd. I am using 24VDC pnp switches with the PDMX-126 board. One switch each for each axis for home/limit. I know most of the posts I read that it is not needed but I like the idea of having Mach3 take care of the racking by calling it at the start of a program if needed. Had a bit of trouble setting up Mach3 to see my other parallel port. Finally got it then had to find out why the motors were not all working. Ends up I did not have the pins set correct. Next it took me a while to get the A axis to run reverse. Finally found that as well. The only thing I need yet is to make the mount for the touch off probe used as a tool offset. That will be next week. Will start looking a dust collection next, I was looking at a JET DC-1200VX-CK1 mostly because of the 2 micron rating. Was looking at a thien separator build to use in conjunction.

Pete,
I had the same problem with the Z axis proximity on machine #28. The issue is that it touches the steel and is grounded on that machine. For some odd reason, the z axis proximity to the spindle can pick up the EMF in that area and cause issues with the home circuit.

Things to do / check that have fixed this issue in the past:
- use a doubled sided grommet (plasitc - non conductive) to isolate the z axis proximity from the frame
- change the debounce # in mach3 config to a higher number 100, 1000+
- (in some cases) add a isolation relay to the proximity circuit

Good luck

Sean,
I just changed the prox to a 12mm. I don't know why but the 12mm works fine but neither of the 8mm would work correctly.

More Pics
First picture is the machine itself
Second is the X stop modified to accommodate proximity switch
Third is the slaved axis stop to accommodate proximity switch
Fourth is the Y axis stop to accommodate proximity switch
Fifth is the electrical panel
Sixth is the inside of the the electrical panel (still needs straightened up)
Seventh is the PDMX breakout board and motherboard for the Gecko 203V