4 x 8 Plasma Table Plans

[Torchhead]

Originally Posted by smilewizard Looking to convert from belt driven to ball screws any suggestions?

On a plasma? One suggestion: DON'T DO IT!

[Apples]

Yeah don't use ball screws on a plasma.

Why, well it's over kill for starters. Because you are probably only going to be using an air plasma. An the accuracy's that ballscrews give you, the plasma will not be able to give you.

Rack and pinion is the most commonly use method of linear motion systems on plasma cutting, oxy and laser machines, probably water jet too.

Why, because its cheap, easy to install and reliable.

Don't go re inventing the wheel. People have been making high end systems for years and only use rack an pinion.

There must be a reason why engineers do things certain ways.

Peter
Australia

[Torchhead]

It has less to do with accuracy than limitations on speeds and the dirty environment of plasma cutting.

You are limited to certain max RPM on ballscrews. ANy ballscrew smaller than 1" and with standard pitch (5 TPI) will start to "whip" at RPM's that are below the top speeds you need for plasma cutting. My 3/4" 6' long ballscrews won't let me go above about 180 IPM. If it we not for Fine Cut Consummables I would not be able to cut 16Ga steel and thinner.

The ballscrews attract the grit and dust and have to be completely cleaned every 20 hrs of cutting. The slides every 10 hrs or less.

Rack and Pinion or belt is MUCH more forgiving about crud buildup and it's easy to get nice upper speeds from them.

My ballscrew table will be converted to router only duty shortly.

I used them because they (at the time 5 years ago) were what I had cheap. They were surplus with the attached servos so they got used. At the time the table was designed for both router and plasma but once I started cutting plasma it has never routed and inch of anything. Too hard to switch over and a complete cleanup of the machine is in order after EACH process.

[smilewizard]

Thanks for the great feedback. Just a update on what I decided to to. I am in the process of changing from a belt to chain drive system. Why I am changing is to tighten up the machine. After speaking to a power transmission guy he told me that belts are not really designed to go back and forth, they a made really to go one direction. I was seeing a slight lead and lag from the belts, when doing rapid moves. This leads to drifting, and not a smoothe cut. I hope to have this completed this weekend and will post pictures of the completed change.

Andrew

[smilewizard]

OK an update. I changed the table from a belt drive system to a chain drive system. I have included pictures to see how I incorporated this. Another change that I made, was to do away with the idlers on the x axis. Basicly now I have two shafts with sprockets on both ends and they are connected with a chain on each end. I have also shown how I did the spring tensioner for the chain.

The results were a remarkable "stiffening" of the gantry, the table is very tight now. I added some of the work I have done.

Andrew

[smilewizard]

A question for the experts, right now my water is 4 inches below the cutting surface. I can fairly easily lower the cutting surface so that the bottom of the plate being cut is in the water. I have a Thermal Dynamics Cutmaster 81 with a hand torch which I use on my table.

I think this will cut down on smoke as well as keep the thinner sheets from warping. Please give me some feed back and let me know if this is a good idea or not.

Thanks

Andrew

[Weldtutor]

Originally Posted by smilewizard I changed the table from a belt drive system to a chain drive system. The results were a remarkable "stiffening" of the gantry, the table is very tight now.

Nice conversion to a chain driven system.

The chain tensioner using the channel bracket is a very ingenious piece of "Kiss" engineering.

Thanks for the project photos.

I'm not an "ex-spurt" regarding the water contact cutting technique, although the discussions seem to suggest it gives very favourable results.

[smilewizard]

Just an update as I am in the process of changing my water pan so that I can raise the water level to the bottom of the product. I have researched alot on this and from what I have read it shows favorable results. I will post pictures when I am completed, as well as update if I got the results I am hoping to achieve. What is everyone using in the water as a water treatment?

Andrew

[Dale Heart]

smilewizard, you've done a nice job.

As for cutting down on fumes... i strongly suggest getting a fume extraction unit (down draft) of if you want to keep the waterbed you need a hood over the plasma with an updraft in place... ESAB have some nice fume extraction units that look like little vacuum cleaners. If you do this though... make sure you have a U bend in the hose so water mist is caught and not passed through the filter.

[smilewizard]

Decided against raising the water up and down in this table at this time. The reason is that I am in the process of building my second table and it will be capable of doing this. You can see its progress on the thread "recently completed plasma table". If business picks up I would probably redesign the water pan to resemble my second table.

I have posted a carving I did with this table using a dremel and a 1/8 flute bit. I just did this to see what I would get. I was impressed by the control of the table. I had purchased a router for this table a year or so ago and had not done any wood until now. This table may become a router/plasma table with a removable vacuum box. I will post pictures of this when I complete.

[Weldtutor]

Welcome back Andrew!

I'll be watching for that new table build.
WT