[DDM]

Ok, Seeing as how my hex rail and skate board bearings idea is going to take me too much time, I've had to rethink how I want to build my machine. I've spent most of the night looking through the Igus website debating which direction I would like to jump. Binding won't be an issue in my design. I have three options that I see I could use on a gantry router.

http://www.igus.com/show_dw.asp

#1 Use the Drylin W 10mm 40mm wide double rail on both the X and Y axis so that there would be 2 double rails per axis. I think I would be fighting alignment problems after reading some of the other posts. Total cost on rails and shuttles about 450 bucks. Static load rating 1079 lbs which is with a complete carrage assembly.

#2 Use the Drylin W Square 20mm single rails for the X and Y axis 2 rails per axis. They claim that the square is better than the round rails for friction and load capacity. This setup would run me about 500 bucks. Static load rating is 719 lbs per shuttle. Looking like this would be my best bet.

http://www.igus.com/show_dt.asp

#3 Use the Drylin T 15mm rail with 2 rails per axis like #2 option. They look like they would be a good route to take other than the price. This option would set me back about 750 bucks but the adjustability would be nice. The static load rating is 900 lbs top and bottom and 450 for the side which is going to be the highest load rating out of any of the options and probably the most adjustable.

So is 250 bucks worth the extra adjustability and load capacity for a machine that might see a little bit of aluminum and steel milling.

[DDM]

Well I've been doing a little more research on the Igus system. I still like the looks of the Drylin T system but having to put one of the sets of shuttles in floating mode doesn't thrill me that much although the load capacity should be enough for my needs but this is just farmer calculations right now.

I was hoping someone has had some experance with the igus system and could offer up some advice. The W square rail looks nice but I don't know how much slop there would be and if by adjusting the shuttles some of the play could be taken out of them. I think I'll call Igus tomorrow morning after I get off work and talk to them about the different systems. I'll keep everyone posted as to my results, may not get much of a reply here but on a search for future reference these posts can be great.

Carl

[Kipper]

Well I only speak for me when I say I looked at the igus sytem and wondered whether it would be rigid enough. I kinda prefer the idea of some of the homebrew solutions cooked up by users and not suppliers myself. I like this "pro" idea however. Jet Rail I believe it's called...

[spalm]

I have not had any experience with Igus slides. The price is really tempting. Someone who built with them is Yukonho. It is a nice machine. Here is a link to his last build:

http://www.cnczone.com/forums/showthread.php?t=15835

Keep us informed of what you find out. Always looking for something new.

Steve

[svenakela]

Depends on the size off your machine, but if you go the Igus-way expect a lot of play. They have at least 0.10 mm play. I have a friend that started out with Igus but he changed, cutting aluminium was out of discussion.

[DDM]

Was your friend using the W or the T? I think I've kinda ruled out the W for my machine because of the slop issue, it just doesn't have the adjustability that I would like. I have yet to call Igus but I've been working on drawings using the T system so I have a better idea on what to tell them for my application. I'll keep you all posted on my progress, it would be faster if I didn't get caught up in the movie I was watching while working on solidworks.

Carl

[svenakela]

The big T-model. They still come with a lot of play and can "stall" if they are mounted too wide.

[MechWerks]

Just my .02 but I used a single Igus slide for a plasma torch gantry. Even adjusted tight, the slide has a lot of slop that just will not go away. It is not a huge problem on the torch since there is never any pressure on the cutting end and normal weight keeps everything in a relative position. If any pressure was involved at the cutting end, the Igus slides are not worth the low cost.

[yukonho]

The IGUS system just doesnt work well for our application. Adjusting the carriages so they dont bind is a bugger, and there is just no way to get rid of the slop.
It took me easily as many hours to get the IGUS rails working at an acceptable level as it would have to just build some skate bearing type rails, which would have worked better....
Colin

[rogerou812]

I saw IGUS 3 years ago at the IWF (google that one) show in Atlanta. Made sense since woodworking creates fine dust and oil/grease don't mix and sooner more than later it seems will failure happen. Thompson, and a couple of other linear people were represented there.

I was creating some woodworking appliances that were put on hold due to the arrival of an infant and the IGUS people were very helpful..and generous. The guy I talked to sent me an 18" sample of the double rail with four bearings and a couple of other linear types.

Again, my applications were put on hold but I still have the rail. Someone else suggested double rails side by side and that is my intention on the z axis. I need to order 4 more bearings.

Call IGUS and go to their site. there are single rails which can be mounted in any configuration of pairs. there are also thompson type blocks for the Drylin bearings.

[mxtras]

You might want to look at these - I have not personally used them but they look like a decent system (?) -

http://www.pacific-bearing.com/produ...oduct.cfm?ID=4

Scott

[schbrownie]

Guys,

Just in case you're still working on this project:

The igus bearings are a type of bearing called a “plane” bearing. For these types of systems, you have two other options: ball bearings and cam roller. Ball bearings come in the same housings as the plane bearings and use tiny ball bearings to reduce friction; whereas the plane bearings use Teflon or other engineered plastic to reduce friction. Cam rollers (aka cam followers) are rolling metal bearings (which also have tiny ball bearings inside of them) that rotate.

One of the biggest downsides to the plane bearing systems is that they don’t like misalignment. If the system is out of alignment, then the bearings simply bind up and don’t move. (I’ve spent lots of hours aligning systems and the only thing that usually ends up happing is that I get frustrated) The upside to these systems is that they don’t catastrophically fail. This means that if they fail, they usually don’t destroy the shafting and there’s no balls to blow out and get all over your shop. The last time I had a ball bearing fail, balls went everywhere and I didn’t realize it… I slipped on the balls and almost fell on my ass. Another great thing about plane bearings is they can get dirty and it doesn’t matter. With a ball bearing, you have to add seals and protect the tiny balls from all dirt and chips. Plane bearings can also run without oil or grease… which keeps the shop cleaner I don’t have to remember to oil my router before I use it.

For just my $0.02 worth… I have worked with most of the companies out there that supply bearings or linear slides and my personal favorite is Pacific Bearing. The guys at Pacific have always been pretty helpful for me and their tech support guys have always looked at my applications, even though I’m not a huge customer (I try to get everything as cheap as possible!!). PLUS my favorite thing is that they are the only company I’ve found that carries all the different types of bearings… so if one type doesn’t work, then I can try another one… without have to go shop for another company (and play the phone game of push 1 for this and 2 for that and finally after 30 minutes you have to leave a voicemail only to hope that maybe someday you’ll actually get someone to call you back). In case anyone from Pacific read this…. Thanks for having someone that actually answers the phone and not making me wait on hold forever. Here is their website: www.pacific-bearing.com


Here are some of the products that I’ve used and how I have used them… I’ll try to find some pictures to post. I went to Pacific’s website to make sure I use the correct product names…. I’d hate for you to go looking for something because I called it the wrong thing!

Pacific makes good products and I’ve used a couple different types of their systems over the past few years. I build a small Dremel mill using Pacific’s mini-rail product. I used their big carriages (20mm) for my X-axis and then used a two of their 15mm rails for the Y-axis. At first I just used one rail (mounted sideways to a square cross-beam) with two carriages on it for the Y-axis, but found that it wobbled too much. To fix this I added another rail with one carriage to the top surface of the cross beam and attached it with an L-bracket. This took almost all of the wobble away and I can barely notice it anymore. It took me a little bit to get the X-axis rails to line up. I called the phone support guy at Pacific and he told me to line up one of the rails as best I could and to install all of the screws, but only snug up the one screw at each end. After that one rail is installed, screw down the second rail and leave all of the screws loose. Then put on the carriages and the Y-axis beam (don’t worry about the Y-axis rails or slides yet). Move the beam from one end of the X-axis to the other a couple of times. If it doesn’t move from one end to the other, loosen the first rail and try again. I’ve found that it’s usually tight in a few places and loose in a few others. Once you have tightened the first end of the second rail and move it to the far end of the X-axis and tighten that end. Move it back to the first end and hopefully it will move smoothly. Tighten down all the screws and you’re done. If not, try to get small sections at a time to work. You can use clamps to pull the rail together or push it apart so that you can screw it down and get it to move.

I’ve also used their redi-rail rollers system. I remember the engineer there telling me that you need to lubricate whenever you have metal to metal contact and that their sliders come with lubrication wipers (which was really nice). I usually use this system with larger tables because it’s easier to line up and it’s more rigid. The plane bearing systems do not work too well when you apply a big torque or moment load to it. I built a system with a friend that was on top of an old ping-pong table. He and his wife did lots of craft fairs and we built him a duplication stand where one half of the ping pong table was for his master model and the other half was for his slave. When you get to build something this big, you really need a rolling system instead of a sliding system because the friction is way smaller on the rolling system. Even their smallest size guide (30mm) was able to carry enough load. For the X-axis, I ended up using one rail on each side of the table with two carriages on each rail. I used a piece of square steel tubing for the Y-axis beam and had two carriages on the rail. We tied the two carriages together using a 3/8” threaded rod so that the slave would move whenever the master moved (the threaded rod was available at the local hardware store and cheaper than a solid metal rod… I suppose we could have also used a dowel rod). The carriage wobbled a little bit, but didn’t cause any errors in the wood more than 1/16”. If we needed a tighter tolerance or if he would have been cutting metal instead of only cutting wood, we could have added another rail either on top of the beam or added a second parallel rail.

I’ve also built some rails using regular bearings and shafting (both plane and ball bearings), but I found that the rail system usually have a lower frustration factor and an overall lower installed cost. The bearing and shaft system usually costs a few dollars less, but requires more work down the road.

Pacific has a whole lot of other cool products and I’ve been waiting for the right design to come along for me to try more of them. I usually build a router and then turn around and sell it after only a week or two (pissing the hell out of my girlfriend… she keeps asking me when I’m going to be done).

Hope this helps,

~Jon