Does this have any chance of working?

[Dman65]

Most of the MDF designs I have seen were using rails, but I was wanting to use the bearing design from the CNCRouterParts page which uses a "skate" built of skate bearings and aluminum.

When I look at this to scale, it just doesn't look like the 3/4" MDF would hold up.

This is only an X and Y axis from the front and side. The front side has pieces visible that are made of MDF, 1/4" Cold Rolled Steel flat, and either HDPE or aluminum.

It is very blocky, because I am not at all good with a saber or bandsaw. I want to be able to put something together that has no angles if possible so I can just get everything square and parallel. If anyone has any tips on how to achieve square and parallel I would love to hear them.

I started this drawing in TurboCAD thinking it would be pretty easy and you would just select something like "add plank" and give it dimensions or something... evidently not It is going to take some learning for me to figure that program out. I did a line drawing about 80% in TurboCAD and then saved as a graphic and touched it up in Photoshop.

On the front view where the gantry comes in contact with the rails of the X-axis, those blocks are the skates. I didn't attempt to figure out how to draw those.

[CarveOne]

After a few hundred hours of using TurboCAD for real project drawings it will become much easier than some other CAD program you just played with for a while. Once you understand it really well, and don't want to change programs, they'll "improve it" with a new revision that makes you re-learn it all over again. They all do that.

In TurboCAD, open the Tools menu and look in the Snap Mode icon list to find one that looks like an asterisk and is the "Ortho" selection. If it is in an orange square it is enabled, if no orange box it is disabled. One click turns it on and another click turns it off. Enable it so it has the orange square.

Now, in the Tools menu, select the Rectangle tool. In the drawing area, left click somewhere and drag right and downward, then click left to finish the rectangle (or square). Size of the rectangle doesn't matter. Now click on the arrow pointer in the tool bar to the left of the drawing area. (or you can hit the space bar) This is the Select tool. Left click on the rectangle you just drew to select it, then go down to the bar below the drawing area and change the Size X to 12 (or 12.0) and change the Size Y to 12 (or 12.0) and then press the Enter key. The rectangle will change to 12" by 12".

Ortho locks drawing tools to only horizontal lines or vertical lines. If Ortho is disabled you can draw at any angle. Note that you can start drawing a line section in Ortho mode and then switch to non-Ortho mode to change the line direction.

If you had saved it in the native .tcw format you could open it and edit it. Do a "Save As" to save it in .jpg, .dxf or some other format.

No need to draw the carriages. You can download Ahren's carriage drawings and insert them into your TurboCAD drawing directly.

CarveOne

[ger21]

Originally Posted by Dman65 It is very blocky, because I am not at all good with a saber or bandsaw. I want to be able to put something together that has no angles if possible so I can just get everything square and parallel. If anyone has any tips on how to achieve square and parallel I would love to hear them.

Careful layout with a square and a pencil. Cut about 1/16 to 1/8 outside the line. Clamp a straight board along the line, and route to it with a bearing guided router bit.

A single layer of 3/4 MDF will have a lot of flex.

[sonicwonder2000]

Just a question: it seems you have the ability to work with metal since your gantry beam is specified as 1/4" steel. Have you considered forgoing the MDF and constructing it in steel? That gantry beam is going to be heavy and I think that unless your MDF is very thick, you are going to see lots of flex.

[CarveOne]

Originally Posted by sonicwonder2000 Just a question: it seems you have the ability to work with metal since your gantry beam is specified as 1/4" steel. Have you considered forgoing the MDF and constructing it in steel? That gantry beam is going to be heavy and I think that unless your MDF is very thick, you are going to see lots of flex.

As ger21 says, double the MDF thickness. Or consider making MDF box style gantry risers. How the joint is made between the gantry ends and the gantry uprights is very important.

In your drawing, the rails are level with the table top and are directly in the path of the cutter debris. You will need some method of keeping this stuff off of the rails and carriages. They are not tolerant of dust and crud buildup. I'm using them also, and will need to install some sort of deflectors before finishing the build.

CarveOne

[Dman65]

Thanks for the input guys.

When looking at the scale drawing I was thinking I would probably need thicker MDF. Will it work to glue two 3/4" pieces together? I don't think I have seen any 1 1/2" any where.

I don't have any tools for working with steel. The pieces I will be using are pre-cut. The only thing I will be doing with the steel is drilling some holes.

I was thinking there might be a problem with the rails and debris. I was wondering about putting some sort of brushes out from either side of the gantry to kind of sweep in front of the motion. Or maybe just some thin plastic at an angle to deflect.

Of course, if anyone has a simpler boxy solution, I am up for trashing this idea and going with another.

[CarveOne]

Originally Posted by Dman65 Thanks for the input guys. When looking at the scale drawing I was thinking I would probably need thicker MDF. Will it work to glue two 3/4" pieces together? I don't think I have seen any 1 1/2" any where. I don't have any tools for working with steel. The pieces I will be using are pre-cut. The only thing I will be doing with the steel is drilling some holes. I was thinking there might be a problem with the rails and debris. I was wondering about putting some sort of brushes out from either side of the gantry to kind of sweep in front of the motion. Or maybe just some thin plastic at an angle to deflect. Of course, if anyone has a simpler boxy solution, I am up for trashing this idea and going with another.

You can glue MDF pieces together with carpenters glue or slow cure epoxy. Spread it over the MDF with a putty knife, plastic glue spreader, or anything fairly thin. Press the pieces together with heavy weights until cured.

Ahren's bearing carriages are like any other close tolerance rolling system. It doesn't take a large particle to cause a lockup in one or more bearings. The bearing just won't roll over it. Brushes should help, and adding shields to prevent flying debris from flying onto the rails and carriages will help. There is no good way that I am aware of to completely seal the rails and carriages that won't get in the way of some other moving parts. Raising the rails and carriages higher and using shorter gantry supports will help.

CarveOne