I'm still in the process of building mine so I can't say if my changes are going to improve things drastically. I do plan to use double belts, fasten the X-rails together and attach my Y-rails to the work bench. These are pretty common ways to improve performance especially on larger OX's

On the "official" OX drawings, I am measuring 419.538mm from the workbench to the top of the Z stepper motor.

 

The dimensions on my plates match the Openbuilds Rev 80 drawings. They are milled on a Mori Seiki CNC that has no problem holding +/-.0001" tolerance.
One person had bent axles (bolts) running thru his wheels that effected the tightness.
Try different bolts. Try rolling them on a flat hard surface to see if they are true.

Chris

 

Hi All,

Well, I couldn't sleep so I took the gantry apart and checked each plate. The plates are not the issue, and I didn't have any bent bolts.

However, I discovered a couple things. One the y-axis I did not have the offset nuts in their maximum position as I thought. Once I did, the rails moved freely.
On the x-axis I check each plate separately just using a 30mm bolts. With the offset nuts at max they are a bit snugger than the y-axis, but still moved fine. Again,
I probably didn't have the offsets at max as I thought.

However, I did discover that my kit provider did not cut the ends on at least one of the v-slot rails perfectly square. When I took off the right side plate, this was very obvious as one of the v-slot
rails sprung up from the other a good 1/8". So I'm thinking now that the rails were fighting each other somehow and making the x-axis so tight. It's possible they are also not perfectly matched
in length and where bowing some causing more friction. I also discovered that I had dented the v-slot in two place when trying to adjust the offset nuts so I'm going to have to replace that rail now.

As was suggested above, I should probably bolt the rails together and then trim them to match. I hope my chop saw is up to the task.

Thank you for the suggestions.

 

They don't have heatsinks? Suprised they work at all! Are they toshiba chips?

 

I achieved first cut on my Ox BTW. I never received the replacement plates from v-slot europe, but, I pretty much expected that. Shows how reliable it is if you don't actually twist his arm to get something.

Anyway, obligatory video (careful, LOUD audio) https://plus.google.com/111387094029238541867/posts/9zpNX4V65iS
I reverted to using a UNO + grbl, as TinyG2 is pretty much... not working for various reasons...

I've been working on fixing the EM noise issue; it seems that the noise is 'ok' when it's just the motors, but as soon as the spindle starts there is a HUGE EM noise on the 5V rail, and that even trips the limit switches, and the USB of the UNO!

Anyone else with one of these 1.5KW spindle? How did you solve the noise problem? here I'm going to throw capacitance at it, like 40000uF, and see how it goes from there...

 

Hi Steve,

How did you go about bolting the x-rails together? I see people are doing a variety of things including plastic inserts and some sort epoxy.

Thanks.

 

Shielded power supply cable as your lead and a ground from the spindle to your star grounding point

 

Looking good but one thing I notice is the bit is ether very long or you don't have it far enough in the collet

 

Hi Chadderuki.
I very carefully used strong G clamps to tightly clamp the rails together and checked them using an engineers square. Then I drilled through both beams with a drill suitable for tapping 5 mm holes in the center of the front & rear face slots.

Next I tapped 1/2 the holes from the front and the 1/2 from the back, followed by bolting them together from both sides.

Note use lots of clamps to make sure nothing moves when drilling & tapping. This process produces a very strong and rigid beam... This is an in-expensive and relatively quick solution thats worth the effort.

If I was to do it again I would consider using 3D printed inserts to help maintain the alignment in addition to bolting them.

 

I use two 240v filters.

One filter mounted on z axis as close to the spindle as possible. that will send the noise to an earth connected directly to the mains. But you still need everything else shielded From the earth.

And another connected to extension that powers the pc and the psu.

You just have to make sure the filters have are equal or greater that the spindle amps.

Hope this helps.

 

Hi all, new guy here. Just about finished with the mechanical build of my Ox and started some of the wiring. One thing I debated was how to do end-stops. I settled on optical switches and after looking it over, i thought it might be worthwhile to share how i did it. nothing fancy, but a clean setup nonetheless.

 

Just watch out with dust

 

Ahh good point, Hadn't thought of that. Maybe I'll partially enclose them in shrink wrap such that only a slit is open for the slider.

 

They look good! Let us know how they work when you get her cutting.

 

Chad, I had the same problem.. I measured the components and noticed an interference fit with some of the hole locations. You can either have new plates made or open up the hole sizes on your "tight" plates. Hope this helps.

 

The

The .dxf is incorrect, so comparing your parts to the file on the site isn't going to help.

 

Chris stated "The dimensions on my plates match the Openbuilds Rev 80 drawings". Did you compare with that .dxf?

 

The Rev. 80 plates are also poorly designed. However, they should barely work if the hole's true position is within a few thousandths of the print. I would just drill out the top holes a little more to give you the additional clearance needed to loosen up the travel of the carriage.

 

I don't know about the other guys here on Openbuilds but I purchased a set of plates made by Chris and they were beautiful in every way. Fit and finish were on the top of the excellence scale. As far as the design I know that Mark put a lot of thought and time into the design. If I had not liked the design I would have looked elsewhere or designed my own. I have to give Open builds a lot of credit and Thanks as for many of us it would not even be possible to get started in the Maker movement of CNC.
Thanks Guys, Dave(mybuild14)

 

I must be looking at something wrong. When i opened the .dxf file in AutoCAD, it showed slightly less than 80mm...

 

Ok, so I built a variant of the OX and am using the xPro controller. Mechanically my machine went together smoothly and without the belts attached the x and y move smoothly end to end. As with the Routy sitting in my garage, my main issue appears to be in the electronics. I went with the xPro to hopefully solve that problem. I have run the machine on the supplied 12v 10A power supply as well as a 24v 15A upgrade. In both instances I'm getting significant chattering on the Y (long) axis. I'm using GRBL .9 and have $0 set to 255 (Doesn't make much of a difference in the sound but generates a lot of heat on my board). Any suggestions? Video linked below. (Sound is a bit loud)



My X axis has a bit of noise but might be something loose. I'll go try to hunt that down. You may note that I haven't hooked up a router yet as I figured I need to be able to machine are without missing steps or having other issues before I start making chips.

 

did you try to hold your belt in the slot, may be vibration (mine does that)

 

@Bryant, look at this video to see the difference in sound at low and high speed travel of the machine.



Hopefully it makes clear what might be your problem.

 

Are you using toshiba chipped drivers? I had same issue, turned out to be the drivers not outputing enough amps. Apparently they use pull up resistors to get a max current of 4.5amp for very short periods, not for long enough to drive nema 23's.
Changed to decent micro stepping drivers and chattering went.

Or are you losing steps, when the pulley is slipping you get a chattering. Which is highly likely with those grub screws. Mine constantly failed, drilled them out and re tapped them to take m4 grub screws. Miles better

 

Just out of curiosity which drivers did you change to ??

Tweakie.

 

http://www.cnc4you.co.uk/Stepper-Motor-Driver-4.5A,-50V-CNC-Microstepping-CW5045

running them at 100khz

 

So, it looks like it may be a combination of issues. dddman may be spot on in that if I move my Y axis by hand with everything powered down I get some of the sound. I haven't been able to give the high/speed vs low speed a try as I'm dealing with overheating whenever I try to make anything go too fast. Waiting on some heat sinks.

Being underpowered is also a concern as the xPro uses DRV8825 drivers which have a peak Amp rating of 2.5. Right now I have the pots turned up about half-way which allows me to move at about 20ipm with no load. My understanding is even with these drivers I should be able to do better than that. I have some heatsinks on the way which, when combined with good airflow, should help out.

Anyone with the xPro know how to measure the current to the motors? I'm a novice when it comes to the electronics (or pretty much anything else cnc related).

Upgraded electronics isn't in the cards at the moment as the WAF (wife acceptance factor as defined by someone else on these boards) is dropping the longer I have two non-functioning CNC machines sitting around. I had hoped the xPro would be a bit more plug and play than the GRBL shield I was running on my ROUTY but I think heat is my enemy on both. We will see if the heatsinks help out. Hopefully I can get to cutting even if it ends up being slower than my steppers would allow given proper power.