Another new router project

[acondit]

I have been lurking for a while and decided that it is time to get started.

I am building a CNC router. Due to lots of different comments I am downsizing my first machine. I started to build a metal framed router but I decided to build an MDF router first.

I have resisted spinning my motors so far.
I have a bunch of Thomson linear rails and bearings, so I am going to use them instead of black pipe.

My X-axis and Y-axis will both have 1" rails and bearings mounted on Thomson rail stand-offs. My X-axis rails are 48" long and my Y-axis rails are 32 1/2" long.

My Z-axis rails are 3/4" x 18".

I have mounted my X-axis rails on the MDF base piece. There are two SPB-16OPN on each side connected by a pieces of 1/2" x 5" x 34 1/2" 6061 Aluminum.

{Edit}
I added a picture of my design. I still have to figure out the stepper mounting.
{End Edit}

Alan

[acondit]

I have started putting together the gantry. I am still trying to figure out how to insure that my top surface (work table) is precisely parallel to my bottom surface (rail mounting). I am thinking about leveling my Y-axis rails in relation to my bottom surface and using a router mounted on a temporary fixture sliding on the Y-axis to machine the precise height of the end supports (MDF at ends of X-axis rails). Any suggestions?

[the_paco]

Hi acondit!

How about not to bother yourself with this aspect and just machine your sacrifial table top (?MDF?) once your rails (Xs and Ys) are parallel, straight and maybe leveled? I have a different machine but that's how I do it whenever I installed a new spoilboard or when I re-surface it every couple of days. Once you had it machined, you can adjust the Z (according to the ridges left if there's any)...

Maybe I'm missing something about your setup though...

Can I inquire your source for Thomson rails?

[acondit]

The_Paco,

I bought the thomson rails and bearings on E-bay. I bought a unit that included a pair of 66 inch rails, supports, 4 bearings and a mounting plate. Then I bought an individual rail that was 48" with two bearings and supports. Then I bought a couple short rails, supports and 4 more bearings. I cut one of the 66 inch rails down to 48" and cut the other one in half to give me two 32 1/2 inchers after finishing the ends. I am hoping that I will end up with a cutting area that is just slightly larger than 36" by 24".

I have been gathering parts for over a year and finally got to where I think I have most of the hard to obtain things that I need.

I may end up having to just mount the top surface and machine the cutting area but I am hoping that I can get the whole surface pretty close to parallel so that I don't have to lose the hard surface of the MDF for a work surface.

Peace,
acondit

[acondit]

While I am trying to figure out some of the other stuff I made an Acme tap out of a piece of my Acme threaded rod, so that I can tap some plastic drive blocks. I set it up in my dividing head and milled four flutes in it and then cleaned them up with a jeweler's file.
Alan

[mxtras]

Pretty creative on the tap!

Nice thread so far! Keep us posted.

Scott

[acondit]

I am building a torsion box to support the top layer of MDF. I used 1/2" baltic birch for the runners. I am using 1/4" Luan plywood for the two skins. I glued on the first skin and am about ready to glue on the second skin.

Before I glue on the second skin though, I think that I will mount the box in the frame. I am thinking about drilling through the end supports and using about 4 1/4" T-nuts on the inside of each end. I don't see any way to install the T-nuts after I glue the skin on. I guess I could cut a few access holes through the skin but I would rather not have to.

[acondit]

I realized that to get a good surface, I need to have the x-axis rails parallel and in the same plane. The fact that my gantry travels smoothly down the rails would seem to indicate that they are parallel and in the same plane but what I hadn't considered was the amount of flex in the bottom MDF sheet. When I placed a machinest level on opposite rails they weren't level and weren't level with each other. What to do?

Well I decided that I needed a good work surface that was large enough to sit the router base on, that I could level in both x and y directions.

Since I was planning to build a larger router after I finish this one, I decided that the base frame for that router would be a good surface to build this one on. So I have started the frame for router two before finishing router one.

I had some good adjusting screws that I removed from a Navy surplus rack cabinet. They should make good adjusters for this frame.

I built the two long sides first, ensuring as well as possible, that the legs were square to the rails and all in the same plane, then welded them up.
Then I welded on the adjusters. This allows me to square up the whole frame. Then using a machinists level on the top rails, I am able to get the top surfaces of the rails level within 0.0005 / 10". Then by putting in the cross rails and leveling the frame all the way around and squaring the corners, I should have a level top surface for later mounting the rails for the larger router.

This should provide a good working surface for finishing construction of the MDF router.

Alan

[acondit]

Here is the Acme nut. It works fine. I had to put it in the freezer three times though before I could cut enough to let it turn without too much resistance.

[acondit]

I got my 2nd router frame welded up. It seems to be nice and square. I was able to get the surface leveled in both directions with a machinist level. So, I should now have a good surface to use to put together my MDF router.

I built the frame around the MDF router which was sitting on saw horses. When I finished the outer frame, I lifted the MDF router up onto it and finished the rest of the frame under it.

[acondit]

I have started mounting the Y-Axis rails. I leveled them in relation to my base board. I intend to mount my machining surface parallel to my base board. I will mount my torsion box (minus top skin) between the end boards as close to parallel to the base as I can get it.

Then I will use the router to take a light surface cut across the tops of the torsion members to insure flatness. In order to do this, I plan to use the router mounted on a temporary fixture that slides on the Y-Axis to insure that the top of the torsion box is flat before I glue on the top skin.

The problem is that my fixture has to be reversible so that I can reach both ends of the torsion box. The one end is basically no problem, but I still have to figure out how to reach the end at the back of the gantry. I have one idea but does anyone else have any ideas?

Peace,
Alan

[acondit]

I am in the process of mounting the torsion box. I created spacers to make the bottom of the torsion box parallel to the top of the base board.

I am going to drill 4 holes in each end and use 4 T-nuts on the inside of the torsion box at each end for mounting. Then when I glue on the top skin, I should be able to fasten the torsion box in place without having to drill access holes.

Alan