[DSL PWR]

Running a bobcat will get borrrrrring. That type of work is typically seasonal. If you can get a few steady part runs, you'll be busy year round. I take it you have approched some mfg outfits to see if they will contract you? If not well...

[Johnuk]

Roughly how much did all the steel come to? It looks excellent, but it looks quite expensive.

I'm at the frame stage with mine and am thinking about which way I should go.

Best wishes,
John

[InventIt]

Well, if you decide not to finish it, you could stand it upright and make one heck of a shelving unit out of it
Seriously though, it's looking good. Finish building it. If you don't use it after it's built you could always sell it.

[Apples]

Yeah i have been so busy working in the garden putting up the front fence that i havent had much time and money. I have just got up my new shed, 6x9 (20'x30). So thats where she will go. I have been thinking of using angle iron with those dual-l-vee bearings to run the gantry up and down. This should be good enough shouldn't it?

[shockwatch]

Hi Apples. What are you considering using for the rails?

[Apples]

So far the steel frame has cost me $650 AUD. I have saved up some cash and I am now ready to get some linear motion things happening.

I intend to use those abec7 skate bearings. I am thinking of running them on a pipe, with the bearings spaced out at 120degrees each.

What kind of pipe should I use? Will aluminium pipe be okay? or should i use mild as it might last longer and not wear as much?

Ideas please...........

[Apples]

Hi all.

Well it has been a while since I have last worked on my plasma table. I am trying to think through a small problem, any help is appreciated.

As you can see in the photo's below, I have two bits of angle iron with a round bar just sitting on top of it. The angle on the outside was just tack welded on, so the other angle and round are just sitting there. In another photo you can see that I have drilled and tapped a bolt in the round bar. A total of five bolts have been tapped into this bar. Here is my problem.

Originaly I had planned on having the angle iron spaced apart by the thickness of a length of 13mmx13mm box sandwiched between the angle. Then the round bar would sit on top. The bolts that have been tapped would hang down between the angle. Then the box would have to have holes drilled so the bolts that hang down off the bar could pass through the box. The bolts could then be inserted through the box and upwards into the bar to tighten and hold it all togeher.

The problems that I see with this are:

1. I might have a problem with tightening the bar evenly and this might cause the bar to flex.
2. The bar will sit lower because the angle is further apart. This means that I might not be able to have three bearing spaced evenly apart. The two bottom bearings would prevent the carrage/truck from lifting up.

What I would like to do now is to just tack weld the round bar onto the angle like how it is sitting in the photo. This is quick and easy and becasue the angle is butted together this allows the round to sit up higher giving access to allow three bearing to be evenly spaced at 120* apart.

Will the heat fromn welding the precision ground bar (20mm +- 0.013mm) affect the accuracy of the rail? Will this be much to worry about as it is only a plasma table not a router/mill.

You thoughts please.

Cheers, Apples

Peter, Queensland , Australia

[ajwaverider]

I would try another way to mount the round bar to the angle other than welding.The heat just from tacking could cause the bar to warp and ruin accuracy. Im not sure how well the angle is formed at the ends,usaully the 90 degree angle is pretty straight
but the ends are a out of shape. After you get it setup how will you make ajustments if needed?

[vladdy]

One way to get 'some' accuracy in the welding of the round bar to the double angle iron would be to use a spacer in between the angles, slightly lower than the bar so it doesn't interfere, in this way the bar will be held between the two straight edges in sort of a 'cradle' thing-a-ma-jig

the pieces have to held quite tightly when welding to reduce any possiblity of 'permanent' distortion....

If all you are doing is plasma, there 'shouldn't' be any upward load, so two sets of bearings on top may be all you need, but then it wouln't be very suitable if you decided to convert it to a router or other type of 'contact' maching.. the bat could even be skip welded to the angle irons, no tie down bolts would be needed..

drawback is very little adjustablilty for that 'oops' factor..

quick example..

[Apples]

Vladdy,

That drawing of yours is exactaly what I originaly had in mind. The spacer material in the middle that I was going to use was 13mmbox. That way I could bolt the round to the spacer box. Problem is though that the head of the bolt is to large, and I would not fit a socket onto it to tighten it up. So..
Now I plan on having a stud, or in my case it is only a bit of threaded rod which is going to be threaded into the round and then be used as a spacer and hang down and go through the steel box frame of the actual table. Then from underneath I can bolt it up with plenty of room to tighten things up.


Peter

[Hasher]

Hi Apples

For another idea how to make your X axis take a look at this webpage .

http://www.frontiernet.net/~salterc/cnc.htm
http://www.frontiernet.net/~salterc/slidebearings.jpg

I am looking at making mine with a group of "box transfers" but I am building a Router not plasma table

Project looks great so far !


Paul

[Apples]

I have put my bearings and rails on and can move left, right forwards and backwards!

I will take some photo's this afternoon when the camera comes home. .

[Apples]

The rails a precison ground mild steel that are supported by 40x40x4mm angle.

Both the the long and short gantry's slide very easily up and down the length of the table. I was sitting on it before and was able to "push" myself along very easy. With one push I would just keep rolling along..........AWESOME!

It slides nice and smooth without bumps or wobbles...WHHOOOOO!

The precison ground rods and angle iron have not yet been bolted down. I have to straighten one side. How is the best way to do this? I think that the way to go would be to stretch out a lenght of mig wire and pullit really tight with a turnbuckle or somthing. Then measure the gap between the mig wire and the precision ground shaft with feeler gauges.

To adjust the gap maybe I could tap some bolts or weld some nuts onto the angle iron and rig up somthing so that I can just turn a nut and the angle iron slides in or out for adjustment. Hey maybe I don't need to go that far as such. I could probably just bolt the angle down lightly and then adjust with a hammer/block of wood for straightness against the mig wire. Then once it is straight I could tighten up the bolts and nuts.


Let me know what you all think, she is really starting to come together now. YES YES YES!

[ajwaverider]

Hey Apples!Nice to see some more of your progress.How did you end up fiting the rails to the angle?

[Apples]

as of yet the rails are not bolted down. I have decided to get the rack and pinion and motors all going first just to see how it all goes. Then i will adjust the rails for straightness and bolt them down etc.

[CanopyFx]

Apples
Do you have any drawings on how you are going to mount the Rack and Pinion? I am building a similar table and would liek to see your ideas for the drive system

Joe

[dgalaxy]

i was wondering the same thing man that is a awsome table

[Apples]

Joe

I plan on supporting the rack, by bolting it to some angle iron and then bolting the angle iron to the side of the table. The rack will hang witht the teeth down to stop 'crap' from falling in. Then i will most likley have a direct drive setup from the motor shaft to pinion to rack. The motor will hang on a hinge below the rack. Then I will put a spring up to the carrage/truck, which will slide up and down the table and also support the motor, whilst providing contact for the pinion to the rack.

Hope you know what I mean.


i need help on deciding what hardware and electronics to use. I have some cash now and I might just spend some to get the table going. At this stage I was thinking of just starting off with an oxy setup first while cash is low.

[CanopyFx]

I am working on a few drawings that use the same idea. The only difference is I am making a timing belt reduction box to allow for a 10:1 gear reduction. I will post some pictures as soon as they are done.

Thanks
Joe

[ynneb]

The only problem I see with your linear bearing design is that there is nothing to stop the gantry lifting off the rails. I made the same mistake, The ganty will buck when accelerated.

You are doing well though.