Thread: Making a new CNC machine

I was over at bobs place when he open the package it went from to real quick but this has the added bonus of slowing him down just a little the is beneficial I think.

But its all looking good now back to cooking the wife breakfast before i tell her how much I spent with bob yesterday .

Lots of a-drillin' and a-screwin' to do today. Gotta get them thar rails attached afore they goes walkies.

Also, I managed to get a piece of aluminium channel that should do the cross member of the gantry beautifully. It is a little bit longer than need for that, so the extra length will come in handy for making some of the other mounting parts I will need to make.

I haven;t been able to do anything for the last week or so, so it will be good to start everything moving again.

Now, should use my Trade Tools cut off saw to get a nice straight cut on the end of the aluminium channel?

Bob

bugger we forgot about that didn't we, feel free to bring it over when you wokk out the width you need just give me a yell via Email I should be around.

Willy

Originally Posted by Bob Willson

Now, should use my Trade Tools cut off saw to get a nice straight cut on the end of the aluminium channel?

Bob

Have a look and see if there is a business near you who sells aluminium extrusion, chances are they will have a Aluminium Cold-Saw with a Digital Stop.

Accurate to 0.1mm or user error when setting it up

I know 80/20 in sydney will cut aluminium for about $1.50 per cut if its not their stock.

Good thought, that might be a little cheaper than running it over to The Big Willy.

Just got my spindle and VFD. Talk about confusing instructions. I can't even work out what terminals to connect the mains power to yet. It may be R S and E, but not too sure yet.

I remember seeing a few pages on the wiring of spindles on here somewhere, so I will have a look at that first.

Bob

I had what I hope is a bit of luck today.
I went to a scrap metal merchant near me and asked about aluminium scrap and I was really happy to see a couple of pieces of 16mm aluminium that measured 235mm wide * 415mm long.

I have made a sketch of the side that I hope to be able to cut from this scrap. Only the outline, but I hope that it will be large enough to do the job.

The aluminium does have a few holes drilled and tapped into it, but I think I can work round most of that.

The scrap merchant charged me $4 kg for the aluminium and they told me that they pay between $1.30 and $1.40 for scrap aluminium. All up, I paid $60 for the three pieces plus about 15 other pieces of flat aluminium about 100mm * 100mm.

Bob

Not bad, last time I went to my local scrap mob they were charging $5 and paying $0.75 for aluminium.

They rarely ever have anything of thickness, mostly upto 6mm with the odd piece being larger.

Hi Rod

I was fully intending to make the sides out of steel but when I found these pieces of aluminium it was too good an opportunity to pass up, so unless I completely stuff up the sides first go then I will be sticking with the aluminium. Sorry.

However, to do with this, I am not able to get a good cranking out of the pieces as they stand. Do you or anyone else have any thoughts on my cutting off a couple of pieces of the third bit of plate I got and welding them to the top left hand edges of the other two bits so as to increase the width at the top? If I am allowed to do this then I can get the extra width for the crank.

I don't think it would hurt if the sides warped minimally where the weld is done but I am not sure. This also has the downside of costing a bit more for the TIG welding of the sides. Could I please get some thoughts on this?

Hi Bob,
An idea for you to ponder.
I would be thinking 6mm plate either side of the 16mm and laminating the three pieces. This would overcome the existing holes in the plate (more choice for shape) and give you a bit more tapping practice. The fact that it will have through bolts at the top, middle and bottom of the gantry sides you might get away with just glueing the lamination.
The join at the top would be covered by the lamination and hopefully backed up by the end of the Y beam bridging the join.

Brilliant!

I will trawl through the scrap again tomorrow.

Also, even if I have to buy more aluminium (as I will need to) I would think it would still work out cheaper than welding would.

And with the extra tapping practice I should be able to do this for a living soon.

Also, it will make it all look heavier, chunkier and classier too.

I will glue and screw. Can't be too careful.

Thanks Rod

As you can see from the attached photos, the laminating was a great success. There are two tiny bits on the bottom corners where the aluminium sheeting that I got was not quite big enough to cover the whole area but this is so small as to be unnoticeable. I may even just carve that little bit off to make it look like I meant to do it that way in the beginning.

Thanks go to Rod for the suggestion. (On the sheeting bit, not the hiding errors bit)

The sides are only glued at present but I will need to put quite a few bolts through them as well anyway, so that should add heaps of extra strength. Now they are 26mm thick. I will probably need to lighten them by cutting some big holes in them.

As to the actual way I made the sides, I first cut the 16mm aluminium to shape on my bandsaw. I was amazed at how easily it cut, considering that I used my biggest and roughest blade to do it. When they were shaped, I cut the sheeting roughly to shape but left it a few mm bigger all round so that I had a little bit of overhang. I sanded all sides of the aluminium that I was going to glue and then mixed up a batch of epoxy. I spread this thinly over the 6mm sheeting and then made a sandwich of everything. I left it to dry overnight. It usually takes epoxy about 24 hours to cure and attain full strength

In the morning (after about 16 hours) I had a look at it and thought that it was set enough to let me work on it. I put the sides through the bandsaw again and used the 16mm as a guide to very quickly trim the overhang from the edges. After this, I put it to the belt sander using 40 grit paper and took away all the saw marks. When it was mostly OK I put it in the vice and used an orbital sander with 80 grit and then finished it all off by hand with a 120 grit paper. It looks good.

Bob

Nicely executed Bob.

With such a large surface area for adhesion and through bolts top, middle and bottom do you think it needs addional screws to hold it together? I would imagine with the flat solid surface of the ally you got good adhesion, it is not going to be exposed to high heat and the major stresses are likely to be vertical as it is mounted.

Don't worry too much as I would add countersunk screw to hold it together but it would be good to have some healthy discussion on wether they are really needed or just comforting to have them.

I really don't think that it needs any more bolts to hold it all together than are used in the construction. There are about 20 through bolts on each side, plus the glue. Had I been more parsimonious with either of these two, then maybe more could have been required, but as it is, I could tap dance on it and not hurt it at all. I have already tried a polka and a waltz; neither provoked any signs of distress, (Except in the audience)

Well, some things have been going well and some not so well.

I went to Ulrich Aluminium to get a 1 metre piece of 10mm flat bar * 100mm wide. Sorry, we only sell it in 4 metre lengths they said. Damn. .. OK, how much for a 4 metre length then? $140. Get real.

So today, the Big Willy and I went to another local scrap merchant and had a bit of a look around. Well they had heaps of stuff. Some major sized pieces of aluminium and loads of smaller stuff that we could adapt to use for our own nefarious purpose. There was so much in the way of billets and flat sheet etc that we were tempted to spend our entire allowances there. In the end, common sense and the thought of our wives responses prevailed and we went home with only a few Kgs of the stuff.

As you can see by the attached photos I have progressed to the stage where the cross screw is finished and very soon, the Z will also be finished.

After that, the long screw will need to be installed beneath the table. Piece of cake.

As you can see in the pictures, I had not measured the exact internal measurement of the cross member and it was necessary to insert a couple of spacers at the end of the block as otherwise the bearings at the driven end of the shaft would have been inside the end plate.

I am starting to feel really positive about this project now and it seems to be mainly going as it should. The only thing I REALLY hate about this is the way that even after centre popping the holes that I want to drill, as soon as the bit starts to bite into the aluminium it will wander a few thou, and I finish up with a very slightly misaligned job. Most frustrating.

I also had a few issues with the 1.5 KW spindle that I bought from Love-Happyshopping. I could not get the spindle to go over about 11 thousand revs and the instructions that I got didn't seem to apply to my spindle. However, I wrote to LHS and he got back to me with the correct instructions for the VFD. If you buy one of these, then this picture will also help with the wiring

Bob