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View Full Version : BUILD LOG: Redneck Canuck builds a steel cnc router



John540i
14-02-2017, 04:38 PM
I am a design as I go type of guy so I don't have any CAD drawings for everybody to review before I start my build. I have looked at a number of the build logs and have based my design on aspects of those that I liked.

I have included some pictures of my shop so that you can see what sort of tools I am using to do this build. I will say that just because I own a milling machine it does not make me a machinist.

The frame is made out of steel because it is relatively cheap and I have the equipment to do it. The legs bolt onto the main table so that it can be moved. All of the welding and steel work is going to be done in my garage but once I have a rolling chassis it will be moved into my basement.

All of the axis run on round linear rails. The x axis has two ball screws and the y and z each have one.

The main part of the table and legs are done and I am now starting for on the gantry. The table is a bit high. The legs are 36 and I find that to be a good height for a working surface but with the thickness of the table and the adjustable feet the table is closer to 40 I am going to leave this for now and if I find it to high to work on I can cut the legs down.

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John540i
17-02-2017, 07:36 PM
I have made a bit more progress. The machine is now on its feet and the work on the gantry has started. The gantry is made from 2 pieces of 2" x 6" x 3/16 steel welded in an l shape.

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I did break a tap while doing the holes for the x axis rails but was able to get the broken part out of the hole, got lucky there.

I do have a question about linear bearings. On the x axis I have a plate that the bearing blocks bolt to. This plate will bolt to a plate on the gantry. I did this so that I can adjust the gantry. My question is about the plate that the bearings mount to. When I have all the screws in their holes but not tight the bearings move very freely. Once I tighten the screws there is a wee bit of tightness. To give you an idea of how tight if I lift one end of the rail up 2" the plate with the loose screws will slide down the rail. The plate with the screws tight has to be lifted to 4" to start to slide. I am thinking that the plate might not be flat enough or maybe my holes are not 100% lined up. Is this OK or are my bearings going to wear out in a week?

20829

Steel
17-02-2017, 07:56 PM
I have made a bit more progress. The machine is now on its feet and the work on the gantry has started. The gantry is made from 2 pieces of 2" x 6" x 3/16 steel welded in an l shape.

2082720828

I did break a tap while doing the holes for the x axis rails but was able to get the broken part out of the hole, got lucky there.

I do have a question about linear bearings. On the x axis I have a plate that the bearing blocks bolt to. This plate will bolt to a plate on the gantry. I did this so that I can adjust the gantry. My question is about the plate that the bearings mount to. When I have all the screws in their holes but not tight the bearings move very freely. Once I tighten the screws there is a wee bit of tightness. To give you an idea of how tight if I lift one end of the rail up 2" the plate with the loose screws will slide down the rail. The plate with the screws tight has to be lifted to 4" to start to slide. I am thinking that the plate might not be flat enough or maybe my holes are not 100% lined up. Is this OK or are my bearings going to wear out in a week?

20829
Nice machine your building there, steel is never flat and throw in welding and you end up with a even less flat surface !!
Im guessing the plate your using is not flat, you could try shim washers between the plate and bearings, one at a time just find what bolt hole on each bearing makes contact first then use some feeler gauges to shim the remaining bolt holes and also make sure your bolt shank is not binding on the drilled holes in the plate. If you run out of ball screws or rails and bearings i have a full kit for sale 1000x600x330 20mm
That's my thoughts, what do you plan to cut ?

John540i
17-02-2017, 09:46 PM
Thanks for the advice. I might try taking a skim cut on the milling machine to get the bearing side flat. The screws have tapered heads that go into coutersunk holes so if they are off it might pull things out. I think i will try ang get it flat first and go from there. I guess my real question is how much binding is too much ? If i had not compared the bearings with loose bolts vs tight bolts i don't know if i would have thought there was a problem.

I am mainly a woodworker so most of the time i will be cutting wood. I do want to be able to cut alum and maybe a little steel. This is only for hobby use so if that means 3ipm taking 5 thou a pass thats ok.

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warwick
17-02-2017, 10:23 PM
i dont think any binding is good..pop cans help for shims

John540i
17-02-2017, 11:02 PM
Well thats not the answear I was hoping for but that does not mean it is not the correct one. I will see what i can do

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