A Different Machine - Downdraft/water table

[millman52]

Looking ahead, I am going to need a cable mangement system. I like those flexible tracks that follow the gantry back and forth. What is the best place to get them ??

If there are any other systems, I'd like to look at them.

Igus is the most common brand. I found mine on ebay but it took time for what I needed to show up.

I don't really know of other manufacturers.

[flyinwilly]

Installed the x axis belts. Decided to go with Millman and use a bolt adjuster instead of the spring (although I may try it later just to see if it will work). Discovered a screwup when I installed the belts. I forgot to account for the loop around the idlers and drive pully when I ordered the belts so I ended up 5 inches short. Not a big problem since I won't be cutting anything that long.

Next on the list is the electronics enclosure and then we'll get this thing to move (at least a little).

Pics attached.

Willy

[flyinwilly]

Got tied up on other projects (making money) and couldn't wait to get the electronics box finished so I jury rigged the electronics on the floor and IT MOVES. Of course it's just the x axis but it's progress. I tuned and calibrated the motors in Mach3 and ran a couple of test programs. The x axis returned exactly to the beginning (on a dial indicator). I guess my math is correct and the design is valid.

Did run into slight problem with the pulleys. One of the drive pulleys slipped on the shaft so I took all the pulleys off and used Loctite Blue on the screws. Seems to have fixed that problem.

I'll get back to the electronics box this week.

No Pics.

Willy

[millman52]

Got tied up on other projects (making money) and couldn't wait to get the electronics box finished so I jury rigged the electronics on the floor and IT MOVES. Of course it's just the x axis but it's progress. I tuned and calibrated the motors in Mach3 and ran a couple of test programs. The x axis returned exactly to the beginning (on a dial indicator). I guess my math is correct and the design is valid.

Did run into slight problem with the pulleys. One of the drive pulleys slipped on the shaft so I took all the pulleys off and used Loctite Blue on the screws. Seems to have fixed that problem.

I'll get back to the electronics box this week.

No Pics.

Willy

I flat spotted or keyed all my shafts & added a second set screw to all pulleys 90 degrees from the flat or key. The loctite will most likely do the job though.

[flyinwilly]

I did flat spot all the shafts and all pulleys have two set screws. It was the large pulley that came loose. It didn't spin on the shaft but was sliding along the shaft so at least one of the screws was partially engaged with the flat.

Maybe I didn't tighten it up enough or forgot to tighten one of them but they should be OK now.

[flyinwilly]

Completed the electronics enclosure and mounted it on the end of the machine. Still have to put the permanent wiring and switches in but that's no problem as soon as I go out and buy the stuff.

Box has 2 5" fans in bottom from a old computer. They run off the little 12V power supply which will also power the torch relay. I may also run the limit switches through the 12 V supply. The large supply is the 48V which I fed into the 2 terminal strips to the right of it. Makes it easier to feed the little wire lugs in the Gecko 540 which is in the right side. The emergency switch is on the top right.

Still need a plexiglass cover but the Gecko is staying much cooler than when it was sitting on the floor.

Found my flexible cable racking on Ebay. It was much cheaper than McMaster-Carr and looks pretty good. The ID is 15/16 x 1 1/2 -- Should have plenty of room for the motor and torch cables.

On to the Y axis.

Willy

[flyinwilly]

Finsihed the Y axis drive. Came out really well and runs so smooth and quiet. This axis is using 2 linear rails that I got off of Ebay for $35.00. They came with 4 trucks but I am only using 1 on each rail. It took a lot of work to insure that both rails were completely parallel but it paid off. However, I think with a little design change, I could have just used one rail and some bearings on a flat rail. The belt reduction is the same as the one used on the X axis. The plate is the same with the exception of not needing the holes for the V bearings so the plate is several inches narrower.

I said earlier that things were going too smoothly and it finally happened. I forgot to slot the vertical tubes on the gantry to allow the belt to pass through to the outside of the tubing. The slot should have been just below the top rail, about 1.5" wide and .75" high. I've temporarily anchored the belt on the inside of the vertical but it will cause a loss of 1.5" of cutting width and I can't adjust the belt tension. The slot was on the drawing but I just missed it. I'll add it later when I disassemble the gantry to paint the plates, etc.

On to the Z axis!

Pics attached

Willy

[flyinwilly]

It was a hot weekend so not a lot got done ( except for killing a few beers). Finished the 110V wiring. Added separate switches for the motor and electronics. Built a 20' 12 ga power cord and installed and wired the blower motor. Need to build a belt shield and clamp down the greenfield.

Worked a little on the Z axis -got the plate cut, machined, and welded. Decided my design for the floating head was not going to work as good as I first thought so I bought 2 small linear rails off Ebay and I'll use them with a compression spring when they arrive.

pic attached.

Willy

[flyinwilly]

Completed the drive section of the Z axis. Mounted it on the front of the Y axis rails and tried it out. Works great!

This assembly is a 425 oz stepper direct coupled to a 1/2 - 10 acme screw with a delrin nut attached to a piece of aluminum angle which rides on 2 small linear rails (another Ebay purchase). With the gecko microstepping, I had to set Mach3 at 18K steps/inch. It really screams when moving up and down.

I still need to build the floating head but am still waiting for the 2 new rails for the head to ride on. I also decided to add THC to the machine. I'm waiting for Candcnc to come out with the new unit. It's supposed to use the Gecko540 BOB and give you a few more inputs (home, limits, etc) and output relays. It should be available any day now.

The to - do list is getting shorter. The light at the end of the tunnel is getting brighter.

Pics attached.

Willy

[flyinwilly]

Still working on the floating head. The rails I ordered from Ebay came in and they are tiny. They take 2.0 mm screws. Good thing there is 4 per rail on both the rail and truck. I think they'll be OK for Plasma but wouldn't be any good for anything with a heavy load. I'll use them for now but look out for something heavier.

Got the slats and rails installed. My son came up with a great idea about using angle upside down and cutting slots into one side for the slats to sit in. Worked great and was easy to do. Mark it off and stick it in the chop saw and it was done in minutes. Then I just bolted it to the other support that was already welded in and it was done.

Pics attached.

Willy

[flyinwilly]

I finished the floating head with the mini rails and it was working beautifully right up to the point where I dropped it when I was putting the upper stops on. As I watched the head bounce off the bench, the torch holder plate came off (along with the trucks) and lots of very, very small ball bearings went everywhere. It's a good thing I don't have a gun! How the hell did they ever get these things in anyway ?

Well, back to the drawing board. I have a new design using 4 bearings riding in a slot. It should work OK. I think I said that before. Hope to have it done in a day or two.

Pics of the deceased head attached. They were taken just before I attempted to put the upper stops on.

Willy

[flyinwilly]

I managed to complete the latest version of the floating head without dropping it. Actually, this one is a lot more rugged than the previous one. It works better too. I used 4 spare 3/4" x 1/4 bearings that I use for guide bearings on my horizontal saw. I machined a slot on both sides of a 1.5" x .5" x 5" piece of aluminum the length of the block. The slot has .002" clearance over the width of the bearings. The bearings sit on spacers that leave .125" under the slide block. Two bearings on the left side of the block are fixed and the two on the other side are adjustable horizontally. The torch cup was machined to fit the ceramic on my torch and holds it pretty securely. I still need to build a small brace to tie the torch handle down. I tried the machine by taping a magic marker in the torch holder and running some sign designs I've been working on. The floating head worked fine with the marker. I don't think it will need a bias spring but that will be determined when the torch is installed. The extra holes on the front of the torch holder plate are from the previous design.

Basically the machine is ready to go except for the water tray, cable racking, air filters, and the limit/home switches. I also plan to install DTHC which I've ordered from CandCNC and should be here in a week or so. Got to make some money this week so I'll get back to work on it this weekend.

Pics atached.

Willy

[millman52]

Looks like you are coming along nicely on your build. Shouldn't be long now till the real fun begins.

Once you start cutting & things begin to wear together all the weak links begin to show up. At least they did with mine. It would be so nice, before a build begins, to have a crystal ball!!

[flyinwilly]

Haven't worked on the machine for about a week but did manage to solve one problem. I've been looking for a tank to hold the quench when not in use. I thought I would use A RV water tank but they just won't hold any pressure. The water tray will hold about 9-10 gallons so I needed a 10+ gallon tank. Found the HarborFreight had their 11 gal air receiver on sale for $29 so I took the internet ad to the local store and picked one up. The problem with it is that it only has 1 inlet/outlet and I needed 2.

I machined a fitting to weld on the tank. I threaded it for 1/2" NPT which allows me to use standard copper/brass fittings. I drilled a hole in the top of the tank and welded it on. This tank is rated for 125 PSI but this must be the absolute max because the metal is thin. Couldn't be much thicker than 16-18 awg. Held my breath while I was welding hoping I didn't punch through. Pressure tested tank and it held perfectly at 120 PSI.

The feed tube is just 1/2" copper pipe. The fitting is a standard 1/2" thread/sweat fitting. I had to bore it out so the pipe would slide completely through. I then soldered the pipe and the fitting. The end of the pipe sits about 1" off the bottom of the tank. So I now have my air port and the liquid port. Air in - quench out.

Got to get going on the water tray this week and get this beast working.

Pics attached.

Willy

[flyinwilly]

Besides Ebay, where can you buy Sodium Nitrite ? What kinds of businesses use this stuff ??

I plan on making my own quench according to the formula I found here on the Zone. I need to have the quench before I'll use the tank and water tray (when I get it finished).

Any help appreciated.

Willy

[flyinwilly]

Finished up the cable track supports, cable tracks, and installed all the motor cables. It sure dressed up the machine not having cables running all over the place or held up with tape.

I originally planned to have the cable under the rail but when I decided to use the belt reduction, the motors hung down too far. So I had to build a rack above the rail but it turned out OK. Gave me a easy place to tie all the cable down. I drilled a 1/4" hole about every foot or so and tied up the cable with ties.

I used shielded cable with a drain wire for the motor cable so I hope this is enough to eliminate interference now that the cables are above the table. We'll know pretty soon.

The water tray is coming along nicely. Last big thing to complete.

Still need to do air filter, screen filter, torch holder and torch cable holder, limit switches, and some misc painting.

It's getting close.

Pics attached.

Willy

[WSS]

Looks like you will be cutting very soon! You have had a quick build when all said and done. Very nice. Would you call this a portable machine? How hard would it be to haul around to car shows and swapmeets? I can see some potential there.

WSS

[flyinwilly]

I guess you can call it portable if you're very strong. My guess is that it's pushing 400 lbs with everything on it. I can move it on the casters but I am now using 3' pipes and it is still heavy. Wouldn't be too bad with 2 people.

I was moving it around on dolly but the plastic wheels on the casters broke about a month ago. It was pretty much done at that point, maybe 50 lbs less than now.

Interesting idea about the car shows and swapmeets. Instant parts. I was thinking along those lines for art and craft shows but the power requirements and potential liability are issues to consider.

I expect the machine will run very clean, especially on thin material so emissions should not be a problem.

I'll see if I can get some scales and see what it does weigh,

Willy

[flyinwilly]

Completed the water tray and associated plumbing. This was the most difficult part of the build. I couldn't get any of the local sheet metal shops to bend the pan at a reasonable price so I built a brake which did a fairly good job. The only problem was that I had to cut some slots on the bend lines to reduce the force required and then weld them shut later. Had a few minor pinhole leaks which I rewelded and then put seam sealer all around the inside edge. Worked great - hope it lasts.

The other problem was attaching the inlet/outlet to the pan. Couldn't find a standard drain around 1" so I used a flange with a gasket and a liberal amount of gasket cement and bolted it to the bottom. It had 3/4" NPT and I came out with a street elbow into a barb fitting and then into 1/2' TYVEK tubing to the tank. I put a piece of 30 mesh stainless screen over the drain hole and secured it with the bolts that attach the flange. We'll find out how good it is when the sodium nitrite arrives.

Just a few minor things left to do. Need to wire the torch relay, install final air filter, add the torch cable holder, and the limit switches.

Pics attached.

Willy

[flyinwilly]

Finished the torch cable holder (almost-still missing a return spring) and the torch relay got wired. Both work well. Time to cut.

The sodium Nitrite arrived and I mixed up a batch of quench, loaded it into the tank, and proceeded to make scrap out of perfectly good sheet metal.

I quickly found out that your problems are not over once you finish the build. It's going to take a while to learn how to run this beast.

The good points.
The downdraft works very well - zero smoke and fumes off the table.
The machine moves very precisely - no jagged corners, etc. Very smooth cuts.
Water system works very well - no leaks and relatively quick to load and unload the tray. I use about 10lbs air pressure.

The bad (or not so good) points.

The air filter is WAY TOO Small. It restricts the air flow too much so I had to move it away from the opening. I still need to finish the shroud to go around the air filter frame. The filter catches the real fine stuff but the smoke / ionized fumes are released into the area and set off the smoke detectors right away. The interesting thing is that without the blower, I ran for 30+ minutes before they even peeped. The downdraft works. The filter in the pic was pure white when I started and 30 min later it was brown. I am leaning toward a flexible duct into a filter box with several much larger filters. I have several configurations in mind and will need to try them out.

I really need a pendant. Due to interference from the torch, I had to move the pc about 20' from the machine. Good thing I bought a 25' cable. It's very difficult to see the torch holder to zero it out (haven't put the limit switches in yet) or set a new home position.

Have a problem with torch not lighting every time. It lights when you hold it by hand every time but not when it's in the holder. It's a contact start torch and I had to modify the Sheetcam post processor to lower the torch to contact and then back to cut height. That part works OK but it still doesn't light every time. Any ideas on this issue will be appreciated.

Need some type of clamping system for small pieces of metal on the table. Got the tip caught severl times and moved the piece. Anybody got any good ideas about clamps for this ???

I suspect that I need additional grounding. I am going to sink a ground rod but I'm not sure where the machine is going to end up in the shop so I'm reluctant to drill a hole in the floor right now. I think I'll just run a ground strap to the nearest water pipe. I haven't had any problems with the machine electronics, just the PC.

I ran all my test cuts on 18ga mild steel at 150 IPM and 25 amps. Got a nice narrow kerf , no bevel, but more dross than I would like. I'll try some more setups and see what works best.

Still have a little bit of painting to do. My THC should be in next week and that might solve some of the issues with the torch. At least it won't move without an arc OK and it should reduce the dross.

Pat Patriot was the very first cut! He's about 4" tall and 8" wide.

Pics attached.

Willy