Small rigid router - Design advise needed

[mitchejc]

Thanks for the advice Jazz. OTT... please see observation below:-)

The granite slab I welded on is pretty flat and judging from that the two areas where the 2 X base plates will be welded is very much on the same plane, so no significant twist. I would say definitely less than 0.5 mm which is great as I was prepared to deal with 2 or 3mm if I had to. My plan is to weld in the 10mm base plates and then let the gantry settle under its own weight on top of the two alu blocks that sit on the linear guides with metal epoxy in between and release agent on the alu blocks. That way I should get a very good mating surface there and not induce stress bolting it together.

Two observations that might help other newbies.
1) Parts looks a lot more bulky in real life than on your little cad drawing. If you go with 'looks about right' on your cad, it will translate to 'way over designed' in real life.

2) Holding the parts for welding with threaded rod works well but put washer and maybe copper slip on the nuts as they may bind due to movement during welding which makes them hard to remove. I had to cut one rod to release the longitudinal stress that caused two nut to lock up completely.

3) Early in the weld a thin tag weld broke in half with a very loud ping sound during cooling, and I thought this is the beginning of the end as the offset on the broken tag was quite obvious. I did the opposing welds and when that cooled the tag had moved back to almost its original position and you could barely see the hairline crack where it broke.

[mitchejc]

How do I change this thread into a build log or should I just create a new thread under build logs to post my progress pictures?

[EddyCurrent]

How do I change this thread into a build log or should I just create a new thread under build logs to post my progress pictures?

Send a PM to Lee Roberts and ask him to move the thread.

[mitchejc]

Thx Eddy, will do.

[JAZZCNC]

My plan is to weld in the 10mm base plates and then let the gantry settle under its own weight on top of the two alu blocks that sit on the linear guides with metal epoxy in between and release agent on the alu blocks. That way I should get a very good mating surface there and not induce stress bolting it together.

I use this method along with shimming all the time and it works great but don't use release agent your better with a thin film of plastic between, Cling film is what I use. Release agent doesn't always release good enough and can affect the epoxy curing, try a sample first if you do.

[Boyan Silyavski]

Parts looks a lot more bulky in real life than on your little cad drawing. If you go with 'looks about right' on your cad, it will translate to 'way over designed' in real life.

That's true. Same happened here. For second time

I did not have internet for a week and see now that the build goes very well. I will call you if i need to design spaceship

[mitchejc]

Hehe, yes silyavski call me for the help on the spaceship design just make sure you buy big rocket engines as the ship might be a bit on the heavy side :-)

[mitchejc]

@Jazz
Thanks for the cling film plan, it works great and is a lot less effort than the release agent. Yesterday I was mating the surfaces where my x sides bolts to my frame and I already laid down the epoxy when I realised I don't have enough cling wrap left and had to make a plan in a hurry so I ripped a page out of a magazine that was lying there. That glossy paper worked remarkably well. The paper obviously stuck to the epoxy side but I removed it with a wet cloth afterwards. Funny thing is the ink remains so you end up with an inverse print on the epoxy surface of what was on the paper.

[mitchejc]

I really want to put sand in the three sq tubes in the gantry but I'm getting worried about the weight of my y and z. I'm not actually at the point in the build where I'm going to put the sand in but I need to decide now if I'm going to as it affects other choices. I know its a bit late in the process but I'm a bit shocked after actually totaling the weight of my y and z components. Comes out to +- 128kg. The sand will add another odd 20kg's. I'm willing to sacrifice performance for cut quality but maybe I've taken it too far. Not sure if I completed everything correctly but for my X calcs the motor calc spreadsheet turns red (margin of 2.5x instead of 3x) when I fill in my specs but I don't think its accounting for the fact that I have two motors? Will I be ok with this or should I rather reduce weight and not put sand in?

[mitchejc]

Sorry, realised above was a bit of a daft question. The spreadsheet does not allow for dual motor but obviously I can just half my weight for the calcs if have dual motors, so after redoing the calcs all looks fine and I'm doing to fill the sq tubes with sand.