I'm building off of the pinion example build shown here: http://openbuilds.com/builds/v-slot-belt-pinion-example-build.97/ but with a 20x20 rail, and the mini v plate. The same exact set of components is shown being assmebled in the first build video shown here: http://openbuilds.com/builds/mini-v-linear-actuator-build.48/ So - its all gone together nicely so far. Things 'fit' well enough except for the carriage itself. It seems that the eccentric spacers don't actually adjust tight enough for the wheel to securely bite the rail. It gets close. But I need another .5mm before there is no "play" on the rail. Have I done something wrong? Has anyone else seen this with the mini-v plate before? I may be understanding something! Attached is a photo of what I built so far.. notice anything wrong?
Not a great photo but everything looks appropriate. You might contact the store letting them know of your issues and ask it they can set up a mockup to see if they can dublicate the problem. You can either email http://support.openbuilds.com/support/home or use the contact form on the about us page (or both). There may be a tolerances issue at the fabricator level that hasn't been called to their attention yet. Providing an order date may help them test the proper batch.
Troyerta, The mini v plate should have 2 small bore holes and 2 large bore holes. The eccentric spacers have to go to the larger bored holes so the bolt has enough room to travel as it rotates to achieve its fullest possible adjustment. If the eccentric's are in the smaller bore hole this would limit the bolts travel to adjust. If you just stick a bolt in the holes you will see quite a bit difference in how much movement their is from small bore to large bore. Something to check, you may have already tried this. Just suggesting a possibility. The video shows the proper orientation of the plate, bolts and eccentrics. Hope this helps.
Any chance your axle bolts may be coming or are staying loose? The picture seems to show the bolts aren't long enough to get to the locking part of the nuts. Just an observation.
Hi Troyerta, did you solve this problem at all? I have just built a Mini V Linear slide, and closely followed the video (Mini V Linear Actuator Build, published on Sep 29, 2014 by kram242) and I have found that I can't get my carriage tight either. All of the parts are in the right places and you can see the bolt heads rotating in a full circle (from above the carriage) as the eccentric spacer nuts are rotated, but even when in their most "innermost" position, the carriage never becomes completely tight. Does this mean that parts are not the right size? I thought that these things would all be made the same?
It is hard to say where the problem lies but it may be a supplier tolerances issue. Which wheels are you using (black or clear) and what size rail are you pairing them with? As a stop-gap measure, I would suggest loosening the non adjustable wheels, pushing them as tightly as possible toward the inside and re-tightening them. There are generally a couple of tenths of a mm of slack that can be removed there and this may be sufficient to solve the problem.
The bolts were long enough. The problem was definitely in the eccentric spacers. So whether its a design issue, or a manufacturing issue - it doesn't matter to me anymore. I was using the black mini v wheels and all. Adjusting the non-adjustable wheels in towards the center as closely as possible did not provide a noticeable difference. As you can see, the load on the sled a NEMA 17, but on the other side, I mounted large laser with its heatsink. This balanced the weight on the sides of the sled, but it only encouraged the wobble, and made prints look like hell. See the top row with the wobble in dot height. I ended up lining the rail with electric tape to fill the gap. I lined both sides, and the sled felt very tight as a result. If your stepper mototrs don't have enough current at this point, they won't be able to move. If you can't do more current, just rip off the tape from one of the sides of the rail and it should give you somewhat of a balanced improvement. It took about an hour to do. Use one long continuous strip of electrical tape per wheel run, so you should be able to do it with only 4 long strips per sled. See T-Swift for end results. Makes for a nice reproducible setup.
The tape idea is good creative thinking. You could also drill out the fixed holes to 1/4" and fudge the bolts over. This will provide about .65 mm of closure which should be more than enough.
How very disappointing. Three years ago I purchased mini gantry plates and the black mini wheels to test my design. I couldn't get the plate snug on the 20x20 v slot to keep from "wobbling" therefore rendering mini wheels/gantry plate completely useless. Read some forums, found out it wasn't my fault, built according to exact instructions. Fast forward, in hopes and with some indication from the responses from open builds that the issue was addressed and fixed. I figured I could now buy new plates and eccentrics etc. to start my builds which I just found out they have the same problems. Very disappointed is not the only emotion I have. My hopes of getting into this field with quality products, with precision on an affordable level are still only hopes. Do I only consider the larger wheels versions or do they have the same problem?
Actually, I'm betting the problem you are having is with the fabrication tolerances of the V-slot. I can pull 5 different sticks from different batches over the years and no two will adjust exactly the same. There generally won't be a big difference but there will still be a difference. I suggest contacting the part store for help in resolution. They also need to know when things aren't working right in order to put the pressure back on the manufacturer to tighten things up.
Pretty old post but I too am having wobbling problems with the mini v-slot gantry cart. The o.d. of the wheels are 23.9mm. Are 24mm wheels available?
I would drill the small holes out for eccentrics, then it's all eccentric and more adjustable for square and everything. "If you cant make it perfect, make it adjustable!" somebody smart said that... You need a 9/32 drill bit. Gary
As I noted in a previous post, contact the parts store for assistance. They need to know when things are out of tolerance. Use either the Contact Us page or email at http://support.openbuilds.com/support/home BTW, mini-V wheels should be 15.23mm in diameter.
Unfortunately, I purchased 5 Mini V Gantry Kits where the V wheels will not snug up against genuine Openbuilds V-Slot rail. I have built a couple different CNC machines from OpenBuilds without these issues. I have emailed the part store, and will update with response. Edit: The parts store was quick to respond and is working on a solution. Edit 2: I received 5 Mini V Gantry kit replacements that came fully assembled and tested. These replacements are functioning as they are designed to. It is impressive that I raised the issue on Tuesday and received the parts that Friday. Thank you to OpenBuilds for the great customer support.
