Thread: DIY Solsilva CNC

Hi Craig

You've gotta get rid of that chain.

Ask Chris at Ausxmods what he can do for you regarding a T5 belt setup.

He did this on his own machine so he will be able to advise you properly.

I was lying in bed thinking about your design and whether or not timber was an acceptable material for the rail supports.

Wood is fairly stable along its length, moving only 0.01 percent as it loses its bound water. However, (on the average) it moves 8 percent tangentially and 4 percent radially. (Info lifted from here)

This being so, your rails would grow by about 8% in height, mostly in an upwards direction because the bottom half of the rail is bolted to a leg. Assuming your rails are made from 150mm timber, this would mean that you could expect to get approx 12mm of growth. Even of we assume that the figures are grossly exagerated and you only get 2% of movement, you would still have a difference of 3mm overall assuming that the timber was cut quarter sawn.

So how about keeping a bi-weekly diary of certain specific measured points. ie distance from lower cross rail to top of bed etc so that you can prove me wrong and just a loud mouthed know all.

I agree! That chain has got to go!

my question is, do I go to a belt system or install another stepper and slave them?

Are there any disadvantages in slaving stepper motors? Are they easy to set up?

i have just marked up the table so that I can take a few measurements as you suggested. Results to follow....

Three millimetres is a massive variance! The timber I used is 45 x 140mm laminated F17 structural beams. Being laminated I hoped it would reduce the influence of defects in the timber..... Measurements will reveal all!

The fully supported rails are mounted to 50 x 50 x 6 mm aluminium angle then attached to the timber.

as usual any feedback is most welcomed.

Craig

Originally Posted by Bob Willson

So how about keeping a bi-weekly diary of certain specific measured points. ie distance from lower cross rail to top of bed etc so that you can prove me wrong and just a loud mouthed know all.

Ok Bob... I have been taking measurements on a daily basis at varying times and the results are very consistent.

I measured the centre of the X axis at Y- down to the table, then the centre of the X axis at Y+ down to the table and also across the table (Y axis) between the two X rails and can report that there are absolutely no fluctuations in the measurements.

I used a digital tape measure and the only incorrect reading I had was due to the tape measure not being absolutely vertical.

I will continue to take the measurements over the next few weeks... hopefully we will get some rain and increased humidity to see if that has any impact.

Craig

Hi Craig
Good start, but as the weather has been fairly stable recently I would not expect to see much variation yet.

As you say, if it would rain for a while and then get steamy hot, then I would expect to see some variation creeping (possibly even striding) in.

Did you ask Chris about the T5 belting yet?

Originally Posted by Bob Willson

Did you ask Chris about the T5 belting yet?

Hi, yea he did bob but I don't have any closed belts that large, the open belt can be joined but I don't have the equipment to do so.

I suggested upgrading to a second x axis motor.

This place has T5 belts up to 1440mm long.

And this place can supply belts up to 50 metres long.

However, Ilike Chris's idea of a second motor better. This will remove a lot of the oportunity for belt stretching and it won't cost much more either.

Originally Posted by Bob Willson

This place has T5 belts up to 1440mm long.

And this place can supply belts up to 50 metres long.

However, Ilike Chris's idea of a second motor better. This will remove a lot of the oportunity for belt stretching and it won't cost much more either.

I ordered my 1.5Kw spindle the other day along with a collet set and mount. Just have to read up about the setup now.


A quick modification under the table offered a bit more support for all the extras on the bottom shelf.


I have decided to keep the chain for the X axis until I get another stepper motor and slave them. It seems to be the most logical solution!


Spent awhile checking the squareness of the Z axis today. Very close but not 100% perfect (99.5%). I will have another go when I fit the spindle to get it right.