Thread: New Aussie Build

Try a brake on the z axis so it dosnt drop over night....

Hey All,

Well went and spent some money today for an angle grinder and ended up spending a little more than i wanted to but i got something i can use on anything in the future. Its just a GMC but it was 2400w and had a 230mm cutting disk. So with that and some extra disks, i set to chopping some 70x70mm sections from each end of both channels on the bottom face. Well after getting used to the grinder on the first cut it made butter of the channel(thanks for the tip guys). I did try on the last one with the hacksaw and jigsaw just to prove to myself i had spent the money right, and did i ever. The hacksaw got nowhere fast and the jigsaw blades went blunt almost instantly. So tomorrow will be a quick wire brushing and sanding to smooth metal, then ill add the primer. Then on thursday ill spend the time to finish it with 2 coats of epoxy paint.

So steadily moving forward, getting some stuff done. Next week after the paint dries and i have some time, ill look at trying to drill and tap the rack. Then the two main channels will be complete until i can get around to getting the metal for the legs and cross bracing. Then i'll be in business.

Daniel

Just some updates. Painting the channels came out great. I thought they were supposed to green (SWCTM paint scheme), but it was marine blue. Looks great tho. Very vibrant. Not sure if i should have a top coat but i would think the epoxy paint should be enough. Anyone knowing better, please let me know.

Anyway, im going to organise the steel and welding over the next week. Then the timing belts. So hopefully by the end of Novemeber, the table will be completed and all that will be left is the gantry and electronics. Getting closer now.

Daniel
P.S Sorry forgot to move the broom, but i guess it could be used as a comparison for the table size. lol.

Looking good, nice to see some larger ones for reference when I build mine.

Still in the planning stages here.

Just wondering but wouldnt it have been best to weld everything then paint as the paint will need to be grinded away then repainted after the welding.

Im trying not to weld everything together. There is a few reasons for it. One which i am not 100% sure about was speaking with a manufacturer and he said most of their parts are extruded or milled from billet since vibrations will crack the welds and he recommended i would be better off just having bolts from the frame to the channels. The main reason in my mind was the fact that i will need to transport this machine in the future as we are looking to buy/build a house. The easiest way i thought i would do this (as i wont be able to move it much/nor pay for a removealist) was to make it in sections. Each long side of the frame will be welded together, but each channel and cross strut will be bolted to flanges from these sections or the channel itself. This way it will dissassemble for easy transport, then in the future, i can weld up the frame. Also as it was sitting, it started to rust, and as much as it hadn't set in, i still wanted to prevent rust as much as possible(considering i paid so much for the machining...lol). I still need to drill holes tho, but ill just paint those spots when i get round to it. Good point tho, its mainly just my situation.

Daniel

Im just for welding rather than bolting because I cant drill a 100% accurate hole

Understood about the rusting, ruins everything if it gets too bad.

Not sure about the welds cracking either, you wont get any serious vibrations from it to do any sort of damage I would gather.

Blueray,

Yeah i agree, like i said its mainly because of my situation. As for the cracks in the welds, i wouldn't have thought so either since it is a heavy frame which should dampen the vibs anyway, but in saying that, ive seen cracked welds at my trusty metal fabricators from less vibs and the weld penetrated the metal well so it was almost unexplained, so im sure there is a reason that the guy said it, so it makes me a feel a little better nto welding it up just yet. lol.

Yeah rust is very annoying. Although, i bought a wire brush thing for the angle grinder(not brass but something else), and it made rust removal very easy. )

Daniel

looking good Daniel

I am certianly a welding expert, have tried all types and am hopeless at it, but the machinist who ground my rails flat said to keep welding away from them as the heat will distort them.
I think other have found the same problem.
Just my 1 cents worth ...

Cheers,

Alan

Have to agree with the not welding. Apart from the risk of distorting metals we are trying to build a machine with very low tolerance and welding makes the parts stuck for good. Bolting the components together allows for shimming and other techniques so that we can get perfect alignment. In commercial machines the critical areas are machined flat and true and this is something we are not able to do. As a point of interest my milling machine has paper used as a shim, which has been fitted by the manufacturer, to allign the column vertical to the compound table.

Welding on some parts like the stand is better than bolting as the joint is stronger but if you do weld then my suggestion is to make things modular and split into the critcal components so that adjustments can be made.

The critical components are X axis rails parallel to cutting table and to each other - this is the foundation. Then Y axis rails to X rails (which means cutting table). Z axis rails to Y axis and vertical. It does not matter what is between those three components so long as this relationship exists and to achieve this the connections at these points needs to be adjustable.

Have to agree with Rod. Weld the legs together as you wish but don't weld them or anything else to the channel.

Welding at each end (not the middle) will likely not distort in a manner that matters so much.

However the main thing is you want to be able to shim the joint to get everything spot on.

That is why I like the method of notching the bottom web and extending the leg up beside the vertical web.

Shim between leg and channel as needed. Soft drink cans are my usual shim material.

Greg

Thanks all for the clarification on what to do with the legs. The steel will be bought today/early next week and ill have to get to and borrow a welder or get someone really cheap to knock it up for me. I have also put in a request for a quote for the pulleys and belts for the r&p drives. On this topic, Greg, how did your pinion pulley work in the housing. Did you use bearings and an idle shaft. Any photos to help me out. I know my cnetre distance will need to be 108mm so thinking i might do it with 100mm centres and have an idle roller which will push against the belt to take up the slack. Who knows with the time i have i might need someone here to machining the aluminum since im not getting much of a chance lately.

Daniel

Greg,

What was the centre distance between your pulleys? Im not sure weather to use 100mm or go for something a little smaller say 85mm between centres. Also what were the teeth on the pulleys you used. Im thinking 12 and 48 teeth pulleys for the 4:1 ratio. I did try to find some 7.2degree gearboxes (like on shopbot) but can't find any suitable.

Daniel
P.S Does your machine home using independant switches for the x axis so it squares up the gantry?

Daniel

From memory it was about 100mm

Use an idler for tension adjustment if you don't want to make slotted motor mount.

That would also have the advantage of engaging more teeth on the small pulley. Wrapped more.

I used "T5" belt but should have used "TD5"

See pics for ideas.


And an adaptation that was done to the Mechmate, They usually use a gearbox or drive pinion direct.

http://www.mechmate.com/forums/showt...&postcount=299

Greg

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