Easily adjustable belt tensioners for Rostock Max V2???

[nitewatchman]

I like this approach.

The tensioning loads are spread over a larger area of the top plate. The green block is free to move up and down and reacts horizontally against the blue upright member. The green block can be slotted on the bottom to saddle over the adjusting screw to maintain full travel.

These parts could be either machined or printed. I would consider making them from aluminum on my Tormach.

nitewatchman

[Eaglezsoar]

I like this approach.

The tensioning loads are spread over a larger area of the top plate. The green block is free to move up and down and reacts horizontally against the blue upright member. The green block can be slotted on the bottom to saddle over the adjusting screw to maintain full travel.

These parts could be either machined or printed. I would consider making them from aluminum on my Tormach.

nitewatchman

Yes, if the green block is slotted and lubed, that should solve it.
Excellent idea from the getgo, just needed a little tweaking.

[gajtguy]

You read my mind and I wanted to just post the intitial concept. Here is a view of the pieces with some clearance holes or slots for the bolts... I also extended the base that the pink block would rest on when the belts were loose.

Now I need some lunch.. lol

[esbowman]

I was going to suggest slotting the green block too. Good stuff. My only question is if that will fit in the space provided, and allow the acrylic panels to cover it all? I've been surprised how little clearance there is when you curve that acrylic panel into place. That's been my biggest hangup so far.

[esbowman]

I would consider making them from aluminum on my Tormach.

You lucky bastard you. lol. Which one do you own?

[gajtguy]

Here are the STL files if someone wants to give this a try. It's a first pass anyway and I'm afraid my printer is not dialed in like everyone else's.

I tried to be as precise as possible when laying out the sizes. So hopefully this is pretty close to reality. I also think it would be best to print the "ramps" on the bed surface so it's nice and smooth as they rub up on each other.

I've got to head out for a bunch of bunch of hours, otherwise I'd try it. Any takers?

[nitewatchman]

I would consider making them from aluminum on my Tormach.

You lucky bastard you. lol. Which one do you own?

I have a Tormach 1100 Series II with the ATC, polyphase steppers, and 4th Axis. I replaced a MicroKinetics Express Mill with it. It is churning away as we speak, My son is machining Ductile Iron casting to help pay for the Rostock which I am in the middle of assembling!

This has been a VERY reliable machine that holds surprising accuracy. We have recovered the purchase price several times over running parts for local shops that they don't want to fool with.

"The Wind" - shown below is what it can do with an .stl file. This was about 2 million lines of g-Code and cut with a 1/16" ball nose end mill. The material is Marblewood mounted to Zircote.

nitewatchman

[esbowman]

Gorgeous Nitewatchman! Thanks for sharing.

[Eaglezsoar]

Those horses are spectacular! Damn fine job!

[gajtguy]

Here was my first attempt and clearly I've got several dimensions and screw tolerances wrong. Should be easy to correct and try again. I've got to say that even though this might not be the most important thing in the world, it's really fun being able to 'craft-then-print' do-dads like this. Especially if it works (Time will tell)

[atoff]

Okay, so, at the risk of under engineering something crude and unrefined... why not just go with something like this? Keep in mind, the proportions are WAY off, I just sketched something super quick just to get the idea across. The V2 has this little gap between the top and the middle part of the tower, which the top screw goes into, that could hold everything securely in place, as well as the added stability of the wrap around design. I know it's bulky, and ugly, but it would be an easy install, as it would just slide into place. Easily printable.

[img]http://i.imgur.com/DlHCKGX.jpg[/img]

[esbowman]

We think alike atoff. I'm literally modeling the same design now. Well, not identical, but same concept. Using that 2.5mm gap to mount a wrap around base. Mother's Day will keep me from working on it until tonight, but I think it holds promise.

[atoff]

Awesome, look forward to seeing it. I think it'll work... I'd make sure to make the top beams as thick / strong as possible, and connect the base (which I didn't do in the sketch). The nice thing about this design is that there won't be any potential twisting, since it has the two guides / supports on either side. I'd make the bolt holder square, or match the shape though, that would be a good idea for the sake of creating the pocket to hold the nut(s) in place as well.

I'd start working on it, but it's incredibly difficult for me to stand up long enough to take measurements (back problem), that's the only thing holding me back, and the reason I'm so interested in these adjusters... it would make life a little easier for me.

[atoff]

So, since this thread kind of fizzled, I thought I'd start designing a tensioner myself. Here's what I have so far.

[img]http://i.imgur.com/Sj6Qzbl.jpg[/img]


I wanted almost all parts to be printable, and as compact as possible, so I designed this bolt,

[img]http://i.imgur.com/LKgzcmX.jpg[/img]


but I realized there's just no clearance at the top to make the adjustment, and so it's becoming quite convoluted, where the original intention with this design was to "keep it simple stupid." So, not really sure where to go from here. My idea now is a little over-engineered, where instead of a nut at the top there would be a gear, with a worm gear you'd be able to turn by hand to make the adjustments. Like I said, over-engineered.

[esbowman]

Wow. Love the rendered version. And please don't think I've fizzled out just yet. I've been busy with non-exciting "real" work lately.

I'm up to version 20...lol. I have one that is close...I think. (Seems like every time I say that however, I end up installing the tensioner and subsequently find a big flaw that forces a redesign.) It is not one that is full height though. I tried one like that and found it was tough to install and was right in the way of the wires that protrude out of the aluminum towers. I've attached a screenshot of my latest, if you can make any sense of it. It should fit with the acrylic panels according to AutoCad. Printing now.

[atoff]

Awesome, glad you're still working on it, I kind of fizzled. Kept getting sidetracked, then discouraged. I like your design, I wasn't sure if that little piece would have enough integrity to support the tension, but considering it'll be sandwiched inbetween the top plate, I think that would reinforce it enough, so that should work! As for the wires coming out of the towers. I had actually cut a slot out of mine. Printed it, tested it, and it fit perfectly.

[img]http://i.imgur.com/zjBIQRZ.jpg[/img]

Look forward to hearing back as to whether this one works, rev20 is hopefully the one!

[esbowman]

I thought about cutting a notch too. Yours looks so much better.

I'm a little unsure about the little piece at the top too. Hoping it will have enough strength. I just looked and I'm actually up to version 24. Lol

[esbowman]

Btw, what modeling software are you using? I have Cinema 4D, and Autocad on my Mac but have been looking into Inventor or Modo. I'm usually working on the creative side of things for my business (motion graphics, illustration, animation) but would like to find something more suitable for solid modeling and product design.

[atoff]

I think it'll work... I like your design, it's cleaner, and less bulky. It would be a simple fix if it seems like there's too much force being applied to the top piece, which I really don't think will be an issue.

I'm using Solidworks 2014. I've never tried Cinema 4D, but I'm pretty sure Solidworks would be much easier to use, especially for this type of thing.

[nitewatchman]

The tensioners are looking better with every iteration. These will be a real asset to the machines and will prevent the bearing screws from chewing up the upright when they have been tighten several times.

Great work!

nitewatchman

[esbowman]

Thanks man. It will happen. Version 25 printing now. Lol

[esbowman]

Version 26 is a winner?

I'll let you all be the judge of that, but I do have it successfully installed and the acrylic cover fits!

So, I'm attaching the STL files here. I'm using Slic3r for this with ABS obviously. It took about 2-3 hours to print, but I set my speed pretty low.

Hardware you'll need for this to work:

Qty. 6 — 8-32 x 1" long Thumb (Spade) Screws, or other similar thumbscrew. Bought mine here. http://www.ebay.com/itm/331133117348
Qty. 6 — 8-32 Nylon Lock Nuts. These are for the thumbscrews listed above.
Qty. 3 — 6-32 x 2" long Pan Phillips Machine Screws. These are slightly longer screws to replace the bearing screws.
Qty. 3 — 6-32 Nylon Lock Nuts. (Can simply reuse what you have.)

I wanted something that would install easily, allow easy adjustment, and minimize risk of damage to the printer. The top bracket installs by simply removing the nylon thumbscrew at the top of each tower. Once removed you'll notice that the top tensioner bracket will slide right into the gap that is present between the top melamine plate and the horizontal support for the tower supports.

Before you do anything, please take the time to file out the holes if needed, file the top piece where the support was printed, and build it all prior to installing. You want the thumbscrews to slide freely, and you DO NOT want them to thread the holes.

Once you have successfully dry fit everything, leave everything together except for the bearing screw. You want to install it with the top bracket and smaller bearing brackets together already, or else you'll find it's nearly impossible to install the thumbscrews after the fact. Slide the partially assembled tensioner bracket into the gap at the top of the tower supports, and tighten the Nylon Thumbscrew (original top screw). This will tighten the top tensioner bracket and hold it in place. Note: I made the hole slotted to allow some play, so you should be able to position it inward or outward to align the bearing bracket holes.

Now insert the 2" 6-32 screw through the left or right bearing bracket and the bearing assembly. Use the 6-32 nylon locknut on the other side and tighten it with a screwdriver. Make sure you don't over tighten it though. It really needs to be just tight enough so that the smaller bearing brackets do not have a huge gap between the melamine tower supports, and loose enough to allow the whole assembly to move up and down once you tighten the adjustment screws.

Adjust the thumbscrews now until the belt is tight. Once you feel it's tight enough, you can now tighten the bearing screw a little more. Don't overdue it though.

Photos:

File away the residual support material.

Installing nuts into top bracket. Use a screw to help press it in place.

Top bracket with nuts installed. Notice the slots inside each side wall. This is to allow the bearing brackets to move up and down, but limit rotation.

Right side view. Note the smaller brackets are different. One is left and one is right.

Front view of tensioner installed.

Files:
Here's the STL file, and I'll call it V.026. I used Slic3r for this, and other than having to slightly file off burs from the support material, and opening up a few of the holes, it all fits pretty well. I'm not sure if my machine is 100% calibrated though, so you might need to adjust the scale of this in Repetier by a very small amount if you notice a poor fit. One other thing, you'll notice that I modeled the support material in the STL file. After 25 versions I figured out it was best to not rely on Slic3r to add support material. It should snap right off and you'll just need to sand or file where it was in place. If you guys feel you want it without the support material modeled, just let me know and I'll post an alternate.

rostock max v2 belt tensioner v26.stl

Rostock Max 2 - Belt Tensioner by Eric Bowman - v.026

(141.68 KiB) Downloaded 539 times

Finally, I'm open to suggestions on how I can make this even better. I'm pretty happy with it right now, and time will tell if it holds up. Fingers crossed. Please let me know if you have any luck with this, and please post pics of it installed. If all goes well and you all like it, I'll eventually throw it up on Thingiverse.

Have a great Memorial weekend. I hope you all get the time to print some of these and post pics.

[apostoly]

Excited to try this out!!!

Will be printing shortly

Thanks for putting in so much effort

[Eaglezsoar]

Very good work, thanks for sharing!

[atoff]

Nice job, hopefully I can get the parts ordered soon and give it a try! Definitely thanks for sharing.