[ClockMaster]

The time has come for me to build my first machine from scratch. The goal for this build is minimal tooling required and cost effective. The machine will be desktop sized estimated area 32"x24". All parts will be designed in SolidWorks and assembled before actual ordering and construction. This gives me the ability to scale the size up or down as well as make improvements and changes before the machine is actually built.

To me the most complicated part of any build is the linear motion. Rails and linear bearings can be quite expensive and require custom fabricated parts. My initial idea uses only 8020 parts with some spacers and bearings.

Please have a look and let the journey begin!!!

[ahren]

Interesting design, and clever use of commodity components, especially for the bearing adjustments. I would caution that aluminum is a pretty crummy bearing material. It will wear significantly with repeated cycles, and also tends to vary significantly in thickness along its length, so your wheels may lose contact at points along the travel. This is why we went with cold rolled steel for our linear motion system, which is designed to work with 8020 extrusions.

That being said, I'd love to see how this works out -- it's got to be better than 8020's sliding system, and might provide good intermediate-level linear motion, especially in applications where loads aren't that high (foam cutting, etc).

Best regards,

Ahren
CNCRouterParts

[ClockMaster]

Thank you for the input. I do agree with the fact that the aluminum will wear. A possible alternative would be to use 1"x1" square steel stock. Another alternative to prolong the life of the aluminum would be to use nylon rollers insted of direct bearing contact.

Keep the input and ideas coming. This will be a fun project to evolve.

Couple small modifications and the first version of the frame.

[ClockMaster]

Quick revision before bed. I changed the frame some and extended the slide rails to maximize the cutting area to the footprint.

[ClockMaster]

I've been doing some brainstorming and searching. I have another idea for the bearings but I dont know if what I already have is better or not. Using a 3/8ths steel shaft and a steel pulley this seems like it would work. I dont know how it would affect the precision but it would allow me to use 4 bearings insted of 6 per rail.

[vtx1029]

I just found this today and figured you may be interested.

MakerSlide Open Source Linear Bearing System by Barton Dring — Kickstarter

[louieatienza]

I think you have some interesting ideas. I experimented with patio door bearings and 1/4" plate that I radiused on each edge. Was not too thrilled wiith the results, though someone might be able to better implement it. I also tried sash bearings, which have a nylon v-groove outer ring, but the bearings themselves proved to be a bit inaccurate. I ended up building a machine from Solsylva.com plans, and was happy with the performance for the cost.

I would start with material that might be more consistent in dimension; Ahren mentions cold rolled steel like used in their LM rail system. You could also get ground tooling plate for a little bit more, which is more dimensionally precise.

[ClockMaster]

I am going to mock up a small test rig using the precision shaft with a nylon roller. The parts should be fairly cheap and allow me to see how sloppy it will be. The 6 bearings seem like they would be more stable but I am not sure of this yet. The pulleys would simplify the Y and Z axis but I would rather have less slop and better strength vs simplicity.

[ClockMaster]

I have decided that after looking into parts and different ideas that the simple bearing method will be the cheapest and easiest to design and offer the best accuracy for the price. I will continue with this design and down the road look for improvements. Tonight I will start the Y and Z axis.

[lovebugjunkie]

Misumi offers milled extrusions. Might be an option.

Aluminum Extrusions with Milled Surfaces | Mechanical Components for Assembly Automation - Misumi eCatalog

[pencilneck]

Using a 3/8ths steel shaft and a steel pulley this seems like it would work. I dont know how it would affect the precision but it would allow me to use 4 bearings insted of 6 per rail.

Yes it works, this is how I've done it and I can only suggest it if you can't afford linear rails (as was the case for me at the time). When I use a runout gauge on my mill, I can see a wobble in my X and Y axis due to this set up. Now for my projects, it hasn't been a problem, but I'm sure the runout will not improve with use.

Also, I've run into some binding issues. I've found that if I spray some dry lube on the rollers, that prevents it from happening, but I shouldn't have to do this in the first place.

So... yes, it can be done, it is cheap and it does work... however, there are better ways and you may wish you would of saved up your pennies first time around.

[ClockMaster]

I found a source for some very cheap ($4) acetal pulleys at grainger. My plan is to fit them with some bearings and do some tests. I am willing to deal with some runout as this is my first build. This also leaves pleanty of room for improvements. I am favoring the pulley/rail method vs the direct bearing method. The Y and Z axis with pulleys and rails is greatly simplified. The parts count is cut in half and the design is much smaller and simplified. Everything for now kind of relys on how test rig comes out. I know this is more of a band-aid approach but its also a cost effective learning expierence at the same time.

[jharvey407]

ClockMaster,

Have you looked at using v-bearings? I bought a bunch of them off of ebay from VXB and they work great.

Lot/Package of 8 V Groove Ball Bearing 3/8" (8 pieces) | eBay

[ClockMaster]

I will take a good look into those. What did you use for rails?

I recieved my parts for the test rig. The bearings were a perfect fit to the pulleys but when the pully was tested on the rod there seemed to be a decent amount of rotational slop perpendicular to the rail. The bearings and pulleys were very smooth following the rail but the pulley could be twisted. I will test tomorrow using 2 pulleys but this setup doesnt look promissing so far.

I like the simplicity of the CNC Router Parts setup but I would want the rails cut and drilled on a CNC vs doing so by hand. The v-groove bearing project is also nice but I am not sure if the parts can be ordered yet. This ebay option also looks good.

[ClockMaster]

[QUOTE=hoform22xu;1013087]The bearings were a perfect fit to the pulleys but when the pully was tested on the rod there seemed to be a decent amount of rotational slop perpendicular to the rail.

The pictures arent showing....Can you fix the links?

[jharvey407]

I will take a good look into those. What did you use for rails?

I used the IVT integrated rails from Pacific Bearing on phase 3 of my machine.

Linear Guides Integrated in Aluminum Extrusion Rail Systems, SIMO, Linear V Races, IVT

On the first two machines I used aluminum angle and it worked well, but it didn't last long. You could probably use steel rails.

[ClockMaster]

How would those v-groove bearings work with stainless steel plate? Would the the edges have to be ground to a V shape or could I leave it square?

[RossMosh]

How would those v-groove bearings work with stainless steel plate? Would the the edges have to be ground to a V shape or could I leave it square?

Joe's CNC calls for steel angle iron to be used. Some grind it. Others leave it square. From what I understand, it works fine but isn't without flaws. The steel can wear down over time and obviously is not consistent. It's actually less consistent than the CRS used in CNCRouterPart's system. The next step up would simply be to buy some hardened V-rail. It's readily available and not really that expensive.

You can also look at Glacern SBR which mounts directly to metric 8020 extrusion. Not exactly cheap, but is fairly priced. There is another eBay seller LinearMotionBearings2008 who sells a similar product to Glacern for as good or a better price but is in China so I wouldn't expect the same level of customer service.

One other thing, with the CNCRouterParts system don't worry about drilling the CRS. Ahren now has a drilling jig and the spacing between holes does not have to be perfect at all. The only thing you have to worry about is making the sure the steel is in good condition and isn't all dinged up.

[PaulRowntree]

The next step up would simply be to buy some hardened V-rail. It's readily available and not really that expensive.

RossMosh, where do you buy your hardened V-rail? The only source I have seen around here (Ontario, CA) charges ~$1/inch each, so $2/inch per rail. For me that makes it comparable to supported rails. I would be very interested in a cheaper source!

[zool]

All of what is being discussed is being done with MechMates.

MechMate CNC Router - Build your own with our detailed plans

Lots of builds on youtube

http://www.youtube.com/results?searc...=1&oq=mechmate