16mm Linear bearings

linear hardware

Okay, I’ve received my first batch of linear components to be used for the Marauder DIY CNC project.

16mm unsupported rail and linear bearings came from VXB. Very nice stuff.

The lead screws came from Metal by the Foot (they have a rude picture of a foot at their Web site). They are pretty rusty and one of the two screws isn’t very straight. Not really thrilled. Perhaps I didn’t order the right thing. I had just imagined that parts would have been in indoor storage and would not have started to decompose yet.

I got the delrin nuts from ebay. Turns out I may have ordered the wrong ones as they are 1/2″ ID and I wanted 3/8 since I ordered 3/8 screw. I might see what screws I can find locally in 1/2″ size.

Next I guess I need to slice these to size using an angle grinder or dremel. Might be a bit of a job for a dremel but I’ll give it a try before I buy or borrow an angle grinder.



Linear Bearings for small CNC

I was just looking at the Zen 12×12″ CNC which is made of Polyethylene, just like my big red colored mill.

This machine uses 16mm linear bearings on the X and Y axis and 12mm bearings on the Z axis.

So that’s:

4-16mm guide rails
8-16mm linear bearings
2-12mm guide rails
4-12mm linear barings

The linear bearing cost is easy. 4-12mm is $19.95. 8-16mm is $39.90. So the bearings are $59.85. I’m a little confused why they list two kinds of 16mm bearings and one is twice as expensive as the other.

The guide rails are a bit trickier to choose since they need to be longer than the travel. The 16mm x 60″ rod is $39.95. I suppose this could be sliced into 4-15″ segments.

The 12mm x 13″ rod is $4.95. That can probably be sliced to create the Z axis rails.

So if the above is right, that comes to $104.75. My only concern is that the 15″ rails for the X and Y axis could be short. This only allows 3″ for the the space taken by the linear bearings. That’s assuming the guide rails can be mounted flush which would probably require drilling into their ends. I don’t have tools for that (unless I can figure out how to do that accurately with my drill press).

I just noticed that the Zen is 18x18x14″. That means there is an extra 6″ over and above the 12″ travel. So if I take enough off th 60″ guide rail for one 12″ axis, that leaves only 24″ left for the other axis. So if I split th remaining, that just leaves 12″ guide rails. If we still need 6″ of extra, then there’s only enough left for a 6″ cutting area. So we’d only get a 12×6″ cutting area.

If we want the machine to be 12×9″ or 12×8″ we’d need more guide rail. If we add a 14mm x 30″ at $24.95, that boosts th cost up to $129.70.  But with the 30″ rod we can get a 12×9″ machine. Plus we have 24″ of 14mm rod left over.

But this begs the question of why we are using the 12mm hardware on the Z axis. We could just convert the 12mm bearings to 14mm (same price) and use the left over 14mm rod on the Z axis. We can then drop the 12mm rod (which was only $4.95). So that’s $124.75 if everything is 14mm.




What are these holes on linear bearing blocks

I was looking at the linear bearings on my mill the other day.

What are these holes on the bearing blocks? Are they some adjustment or fastener for the linear bearings?

Could it be to add lubrication?

I’m just curious.

Linear bearings for pick and place system

linear bearings

I’m working on a pick and place system design. I ordered some linear bearings to move the suction heads up and down. They just arrived today.

This is the first time I’ve had linear bearings in my hands (aside from when they are already in an assembly).

They run very freely and smooth. No drag and no play. Very impressive.

Bearings for Marauder DIY CNC


I’m looking at the bearings for the Marauder project.

I was going to use ball bearings like on my laser but I’m told that linear bearings can be purchased for cheap. Does anybody have any better ideas? Are these rods and bearings too heavy? Are there better suppliers to consider? I will do a BOM for the ball bearings as well.

Here is a quick cut of pricing from VXB.

X: $120.00 ($100 if you split the rod 3 ways)
Supported Rod: 12mm, 60″ supported rail $89.00
Bearings: 10.00 each = 40.00

Y: $55.00
Rod: 16mm, 30″ $25.00
Bearings: $5 each = $20.00

Z: $25.00
Rod: 12mm, 13″  $5.00
Bearings: 4 for $20.00

TOTAL:  $170.00




ball bearings and linear bearings


I’ve been thinking of different ways to make linear bearings for the Marauder project. I’m stocked up on ball bearings for my various projects (vxb wohoo!).

inexpensive linear bearings

This seems to be an important issue for CNC systems.

I’m exploring accessible solutions for the DIY community (not to mention my own projects).

I have three ideas so far.

1) A combination of ordinary ball bearings (like yoyo and skate bearings) and aluminum angle. This seem to be okay for laser stuff. I suspect it can work for smaller cnc mill applications. There are examples of using it for larger systems that cut soft material. Seems MDF comes into the equation when using ball bearings and aluminum angle (to make up for some of the shortcomings of the properties of aluminum angle).

2) Plastic bearings with rod. It seems the plastic linear bearings are not very expensive. Price goes up if they or not “closed”. So I’m thinking that it’s possible that this can make sense with the plain rod. I’m looking at sources of rod.

3) Traditional linear bearings with rod or supported rod. This obviously works but it’s very expensive. I think it’s a barrier for many DIY CNCers. So I’m biased against it for this project. I just did a quick look at how much it would cost to buy the rods and bearings for my CNC Mill and it comes to more than I paid for the mill. This could be that I’ve not been very successful at finding the parts. Or that it needs to be purchased in bulk.

I contacted a few companies that have various products. So far, they’re bad at getting back. They have all sorts of glossy pictures at their Web site but no prices. So I guess it’s all custom stuff.

One has tried to get back. I sent them an email with questions. He keeps calling me (and of course I’m in meetings). I called him back but of course he was in a meeting. (What the @#$@#W$ is wrong with email for some people). After calling him twice and the timing not working out, I’m now waiting for him to answer my email. It’s been about 3 weeks. These guys must be used to dealing with a bunch of non-email people or something.

The other’s have not gotten back yet. I will make some more attempts to contact some of these companies. I suspect a lot of it is “designer” stuff. I don’t want to buy a hamburger (or a bearing) for 900 bucks.

We’ll see how this pans out.

I have lots of ideas of how to use ball bearings with aluminum angle. That will be the answer unless somebody can enlighten me.

DIY CNC Thoughts


I’d like to make a simple portable CNC. It would make learning more fun because I could bring it with me and share it with people, plus I could do work when I’m on the road.

I came across this site which has some interesting simple CNC designs. There are a lot of interesting ideas there for cutting soft materials. The catch is the site operator is selling the plans. Some of them look worth buying just to see some of the design details.  🙂

I think linear bearings are a bit of a tricky problem because they seem expensive everywhere I look. You can buy them but then you need to figure out how to mount them. I think it’s a bit intimidating for a beginner.


Here’s another site describing a cool DIY linear bearing. This one is cast but I wonder if this could be an opportunity for “Makerbot to the rescue!”.

It looks printable and I wonder if it would work well for a lightweight machine.

Here is a picture from the site.

Another thing that comes to mind for this one is some sort of angle bracket. Looks like it could be a bolt together linear bearing.

Also, I wonder if this could be done based on 90 degree angle. The bearing would be unstable on one direction but I wonder if it matters or if might be easier to just have 4 bearings in around the circle.

linear ball

I just poked around on the internet a little more and found an example of using aluminum angle to make linear bearings.

Also I came across (March 10) the bearing to the right. It’s based on 8 small ball bearings. I think this might have some potential. You’d only need two per axis because you could just make them long enough for whatever application (rather than using 4 per axis like most solutions).  So that’s just 16 bearings per axis.

Now that I said that out loud, I realize that it might not be price competitive since the real linear bearings are often 20 bucks for four.

And this still uses the same shaft/rail but it wont work for supported rail.

What about plastic? more

Here’s a bearing blog.


Here’s a design that I find pretty easy on the eyes.

Looks like it could be excellent for light work.

I found it here.