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Messages - MidwestAquarium

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1
Ian,

Will do sometime in the next couple days when I can find the time.  Doing some (very quick, down and dirty) type measurements of the gantry arms in relation to the gantry, it appears that things are slightly out of square, so I believe you may be onto something with an askew gantry.  The measurement from the bearing block that rides on the linear rail is also different from one side to the other.

I very much appreciate you time and responses...........I have a renewed ambition to finally figure this thing out and with help from this forum believe I am on the right track. 

Chris

2
Ian,

Thank you for your input. Because I can get fairly accurate dimensions (the 4 sides read as they should) on a rectangle and it is just out of square, I am thinking a scewed gantry is a real possibility.  Especially since many other purchasing this brand have had similar experiences with shoddy worksmanship. Unfortunately the customer service for them is non-existent.

While I am fairly handy and can usually figure things like this out, I am not sure how to go about testing for a scewed gantry.  Aside from checking to se that the main beam carrying the spindle is at a right angle to the arms (not sure if that is the correct term) I am not sure what to look for.  If you would be so kind as to explain what to look for/how to test for this,  I would greatly appreciate it. 

Chris

Chris

3
Rich,

Found the member's doc's and did the calibration today on the motors using the function in Mach. (much easier than doing by cutting and manually changing the number) Thank you!

I will check for backlash in the next few days when I get a dial indicator. I did all checking today by rigging a 12" micrometer in a solid position and running the bit to open it. Did it many times and took an average and entered that reading into Mach to make the adjustment on the calibration.  It was only off a few thousandths.  I did notice that when running the micrometer open in the x-axis that the motor would stop and there would always be a few thousandths gap between the bit and the micrometer jaw, indicating that the bit was bouncing back a bit. This was under no load so I am sure when cutting material this gap may not happen, but it says to me that there is certainly some backlash?  Is this something that Mach can compensate for in the Backlash settings?

We ran a small part and it came out fairly accurate.  But if I run a bigger part, especially with some holes cut in it, the part comes back way out of square, 1/16" at least. I should mention that I am cutting cast acrylic, but that shouldnt have any effect on things.

Stirling,

The rack is not plastic, but the gear that the motor runs is some sort of plastic or fiber, not metal. It was originally on crooked (spun kinda like a bike tire with a bent rim). I shimmed it a bit to get it to turn smoother when I first checked things out. I attached a few pics showing the setup of how the motor turns this gear. There are 2 of these, one on each side of the gantry which runs the y-axis. Each motor has its own driver and while testing it today appeared to be somewhat accurate (not under any load) on both sides. But, when cutting parts (especially ones with any sort of circles) the parts are aout of square.  I am trying to narrow down if it is a mechanical problem or if it could be a driver/motor/other electrical issue.


A pic of the stepper running the x-axis is also attached.....same plastic gear.

This setup, with the plastic gear and the way it transfers the motion through the steel and to the rack, just doesnt seem like a precision way of building a precision machine.

So, my question is: Is there a way to retrofit this machine (without major rebuilding) to a system that might be more accurate? Would new drivers help?  The ones in there have to be some cheap Chinese ones.

Thank you all for the time to give me some advice...should have joined this forum 4 years ago when I got the machine! It has really helped.  Chris

4
Stirling,

Yep it is that machine. I have no experience with other machines and this is really the only one I have ever had my hands on but the gears on the machine (that the motor gears contact) are a plastic, not a metal.  Seems kinda shoddy though I have seen other claim that this same machine works well for them and is made the same way.

Which is the double spur gear and how do they set it to be out of phase? Asking so I can attempt to check it.

I will try and take pictures when I get a chance and post.............wondering if there is some way upgrading these parts of the machine by replacement of something better?

Thank you for your time, Chris

5
Thanks John,

I bought the machine new and nobody else has touched it so I don't think that could be set up to run out of square.  This machine has 2 stepper motors (one on each side) that runs the y-axis.  My suspicion is that one of them has some serious backlash so that they are not running in perfect sync.  Is there a way to compensate just one motor of the axis and not the other if this is the case? I ordered a dial indicator to check and thought I would check it with the motor on the left of the gantry and then on the right to see if there is a difference.

Chris

6
Rich,

Thank you, where do I find Members Docs?

I attempted to set the steps/per manually by cutting a rectangle (many times) and then adjusting the steps until it was close.  Not site if this is the correct procedure or not but I did get things close when measuring a small part.

I was reading old posts and ran across one with a fellow who had a similar problem and resolved it when somebody had him change the CV angle.  what is this?

After running most any program the bit will home back to a position positive in the Y.  That distance is fairly constant regardless if it has run a short programor a long one.

Thank your your help, any responses are much appreciated.

Chris







7
Hello, my name is Chris and I am quite new to CNC.  I have no CNC background at all and am having some issues with our machine and hoping to find some help here. i have had a machine for around 4 years and used it very little for the first few.  It is a Vortech with 5x10 bed with stepper motors and at the time I didnt realize it is lkely a piece of junk, but I am getting ambitious about figuring this thing out. We have been using it regularly the past 6 months but it isnt very accurate and would like to try and dial things in if possible.

First main issue:  If cutting a rectangular part, it turns out to be out of square. For instance, I just cut out a part that is 29x15 with a bunch of 1/2" holes in it.  It comes out at 29x 15 1/16 and is 1/16 out of square. I tried tuning the motors to get them as accurate as possible already but am not fimiliar with all the different aspects.

Second issue is if I set my bit to zero on the corner of the material and run a program, instead of returning exactly to the zero point, it always comes back and sets the bit just short of 1/8" forward in the Y.

I am wondering if this is just a function of a poor machine or something I can adjust to compensate? I have poured over the forums trying to search out the answer and while I am sure it is there somewhere, I havent pinned it down yet.

Any help would be highly appreciated.

Anybody from this neck of the woods (west central Minnesota)willing to do some side work showing us the basics of Mach?

Chris

Starbuck, MN


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