[Grunge-Fut]

Hi

I have just started building a plasma table to take 1/2 a sheet in England thats 1250mm x 1250mm, I have designed it with 1350mm travel on X & Y and 140mm on Z, with 200mm hight between track and table.

the plan is to use a 25mm rail with a rack and pinnion drive on "Y" with a 424oz-in 23 size motor. On "X" Im going to use cam follower bearings on 75mm CRS runners with a twin rack and motors set up on the outside the same motors as Y, and a Merchant dice YZTR for "Z"

I have only made the bridge and mounts at the moment from 60x60x4mm box, I went for 4mm so I could get good tapped holes for all the brackets,

any comments or advise will be welcome.

sorry abouy the state of my workshop,

Steve

[cjdavis618]

Looking good. Keep up the good work!

[Grunge-Fut]

Thanks, I was starting to think I was on my own and no one was realy interested.
Steve

[cjdavis618]

No, not at all. I like to think that your post has spurred them into building one of there own rather than posting.

Nevertheless, your work looks very good and clean. What tools are you working with to build it. It looks like your brackets were cut using cnc of some kind. Was it a mill?

Any plans drawn up yet for the complete design?

[millman52]

Have you started from a kit or all your own design? Progress looks good so far. Looks like you are doing a neat job with your workmanship.

[Grunge-Fut]

Hi Both

Thanks for the vote of confidence, I have drawn the whole thing on autocad myself no kit in fact I dont even have a plasma yet. I had a company on the south cost of england Laser all the brackets, I have a few tig welders a couple of migs a band saw, pillar drill just the usual tools, some of the drawings below hached drawings show bridge at either end to ensure motors clear legs

Steve





can some one tell me how to put the thumbnail photos in rather than the big ones im doing please

Steve

[Switcher]

can some one tell me how to put the thumbnail photos in rather than the big ones im doing please

Try this:

1) "Go Advanced" button

2) "Manage Attachments" button (popup window will open)

3) "Browse" button

4) Find the photo on your PC (you can load up to 6 at a time)

5) "Upload" button (in the popup window)


You have to wait until the upload is finished, or it won't work, the more photos & the larger the photo, the longer it takes to upload.


.

[Switcher]

You can also go back & change your photos that you already posted to thumbnails, just make sure that you have them on your PC before you change any of them here.

If you don't have them on your PC, just download them from your post above, then re-post them as your thumbnails.

You can edit your post for a while after you submit them, I'm not sure how long the time frame is, I do know after a while you won't be able to edit your existing post

:cheers:


.

[Grunge-Fut]

Thanks will try it and see what happens

[millman52]

Your table is only 4' long so it will not be as much of a problem. Someone else might get use of my slat holder arrangement.

My table is 12' long, I wanted the holders to be easily replaceable in case of damage so I made the bolt in & in short sections like the picture below.

The slats don't sit in the bottom of the notches of the slat holders. They are slightly below the top edge of the 2 X 2 box tubing.

This way the slats sit directly on top of the box tube & have the best chance of all being the exact same height. Also the slat holders don't support the weight of the plate being cut, they only hold the slats upright.

[Grunge-Fut]

Hi Millman

I had to read that twice, but thats a real neat Idea, I had to have my slat suports cut in 6 bits not 3 as in drawing, believe it or not it was because of transport costs.
I wanted the slats to run away from me when I loaded table so the metal would slide with out risk of catching or "chattering" so my supports run across so your Idea will work well,

You seem to be using a simalar track and gear to me do you think you coul send me a picture of your gear rack mounting please

Steve

[millman52]

OK Looks like I have my pics loaded in reverse order of what I intended.

Last pic. bottom row: I first made a drilling jig & clamped it to the milling machine table, to hold the rack gear parallel with the milling table for through hole drilling. This allowed me to drill a series of evenly spaced holes the length of my milling machine table travel. then unclamp the rack gear & slide it to pick up my original hole pattern & continue down the length of the rack gear. My racks are in 6' sections.

First pic. bottom row: Shows drilling in progress. You can see in the pic I have already drilled a section of holes & indexed my drill back in the last drilled hole & redy to continue the process.

4th. pic. top row: Shows the racks bolted to strap iron. I drilled & threaded the strap iron to accept 5-40 socket head cap screws. Notice there is a row of drilled holes in the center of the strap to mount the assembly to the table.

3rd. pic top row: Shows the side rail of my machine frame with a row of holes drilled for & threaded 1/4"-28 NF. This is to bolt the rack/strap assembly to the machine frame.

2nd.pic. top row: Shows rack assembly bolted to the frame rail.

1st. pic. top row: Entire front side rail assembly including; Front table frame rail, CR strap bolted to the top of thr rail for outboard gantry linear rail, & the rack gear assembly bolted on.

I wanted all these parts bolted on so they would be adjustable for fine tuning as well as easily repairable if a rack becomes damaged or worn.

If you choose to do something similar I recomend mounting the rack gear to CR strap. I tried using HR strap on the first rack/strap assembly & found the inaccuracy of the hot finished (black) strap a bit hard to keep the bolt holes in good alignment.

If you have questions on any of this, feel free to ask questions.

Neil

[Grunge-Fut]

Thats tidy Thanks, I just need to find gear racks and a mill!! I do have a dore-westbury self build mill that I made from castings as part of my degree, many years ago I assume it still works, but its travel is only some 8" so I could do one hole at a time lol

Thanks for the information on hot and cold rolled steel I never even thought about it

What pitch are your gear racks? I was going to use 1.25 or 1.5 pitch with a 3.86:1 XL timing belt reduction with 425 oz/in stepper motors, I have no idea yet what pinion gear

Steve

[millman52]

My gear racks are 20 pitch 3/8 X 3/8 square. I used a 3/4" pitch dia. pinion gear with 4:1 belt reduction. 740 oz. in. NEMA 34 steppers.

As long as your gantry rolls free & you use a slaved (2 motor) set up on your X axis & also keep your acceleration from dead stop to a reasonable rate I think you should be ok with the 425 motors.

What do you have planned for the electronics package? Drivers, power supply, break out board or boards, etc?

Sorry it's been a while since I have checked up on the progress.

Neil

[Grunge-Fut]

Hi Neil

Thanks for that, coicidently I checked yesterday to see if you had replied

Well I did plan on using CandCNC plama pack complete with THC, but due to some stupid British or should I say european law he unfortunately cant ship here, so unless I come and collect it I cant get one here, so as a alternative Im going to use Gecko drives possibly G202s, with a Cambell Designs THC and break out board, they can still ship to England.

As for power supply Im still confused so I have no idea, it seems to me that I can use prety much any voltage within reason.

As for plasma Cutter I have decided on a Thermal Dynamics Thermadyne Cutmaster 51, it seems to be one of the few avalible in England that dont have HF start

If any one has any recomendations or views I realy would like to hear them, as this forum is my only contact with any one who knows any thing about CNC, as I personaly know little or nothing

On reading your post over and over I have convinced my self I need a miller so this morning I am going to see a Bridgeport and will probably buy it. the first job on that will be to fit DRO on X and Y axis

Thanks

Steve

[Torchhead]

Well I did plan on using CandCNC plama pack complete with THC, but due to some stupid British or should I say european law he unfortunately cant ship here, so unless I come and collect it I cant get one here, so as a alternative Im going to use Gecko drives possibly G202s, with a Cambell Designs THC and break out board, they can still ship to England.

None of the items you listed are RoHS complient and the exemption for "Industrial Controllers" ended in January of this year. If a vendor chooses to ship into the UK items not certified to comply with UK import laws, the person ordering faces possible loss (impound) of the items. It is then up to the vendor to pay fees and get the equipment back, or to abandon it. You need to establish with them what happens if that scenerio plays out: Do you get a refund or get stuck with trying to get the units through customs?.

The chances of it being stopped are probably low but you need to establish who takes the loss. Legally from a US perspective ownership of goods is transferred at the shipping location (FOB).

Your take on the power supply is overly simplified. You need to match the voltage and current needs with the motors and drivers you select. Other features in a supply are desirable like AC side shutdown (remotely) and Dynamic load dump (dumping the DC buss on a shutdown). If you are going to operate close to the DC max of the drivers you need overvoltage protection. While a motor supply can be as simple as a Transformer, Rectifiers and big filter cap, it's not a optimum setup and can expose your system to conditions that could destroy expensive components.

The whole RoHS thing is a technology time bomb looming in the future. The willingness of the EU to adopt it against advice that no-lead components and solder exhibit serious flaws, places it in a position to (have to) do some serious denials in the future. At this point NASA and other Depts in the US where the operation of electronics is mission critical, have banned the no-lead construction because of documented failures. Most politicians don't care if your MP3 player or Cellphone dies in a couple of years and you have to replace it. It may prove harder to explain how a $150,000,000 fighter jet falling out of the sky can be justified....on the other hand I'll bet the rules are different for those devices.

Sorry didn't mean to rant on.

We made our decision about shipping complete units to the UK based on reliable reports that they are zealously applying the rules. Since it's totally up to the particular agent and their understanding of the rules it becomes an expensive gamble. It's one thing to ship a small breakout card or a few motor drives. It's another to ship a 65 lb power unit and Digital THC package!

TOM CAUDLE
www.CandCNC.com

[Grunge-Fut]

Hi Tom

I’m sorry Tom I honestly was not having a go at you, we had this discussion via email some time back, and I sympathise with your position, the analogy you made then was "boxing with one hand tied behind your back" but I would still like a THC and to my knowlege no one in England makes one

Is there any chance of supplying as a kit i.e. a board and a bag of components, resistors, diodes etc? for me to assemble

I did plan to make power supply if I could find some plans, dose any one have any or know of any?

Steve

[Torchhead]

Sorry, GF I was not aiming that at you as much as the mindless bureaucrats that put themselves in charge of the us. It frustrates me to see stupid rules, poorly though out, cause a hardship on the guys trying to do something for themselves. I don't want this to turn into a RoHS or government bashing thread.

I can supply you with sub-assemblies as replacement parts. Sub-assemblies (populated and tested PC boards) and cables can be assembled to do what you need. It's not a "kit" and would be shipped in two separate shipments.

The boards mount in the case and onto the pre-routed front and back panels. Everything plugs together with keyed ribbon cables.

I can also supply you with replacement parts for some of the electronics of a power controller. I can give you specifications for a transformer and other large components.

I know I have your e-mail but send me another if you need more details....

TOM CAUDLE

[millman52]

Hi Neil


On reading your post over and over I have convinced my self I need a miller so this morning I am going to see a Bridgeport and will probably buy it. the first job on that will be to fit DRO on X and Y axis

Thanks

Steve

I'm sure I could have built a usable table without a complete machine shop. I just happen to have one & is how I earn a living.

I'm sure there are people that think I have gone overboard with milling, drilling, other machining & have over complicated things. Well that's fine. I just did it my way.

As an end result though I have a machine that will Oxy cut very accurately. It gives me cut edges that are almost kerf line free. Yes there are lines but very minimal. In fact as smooth as my automatic saw will deliver across the end of round stock.

I am of the opinion, if you want accuracy the table needs to be built as backlash free & as smooth operating along each axis as a milling machine or lathe. It don't need to be as rigid because there no cutting forces to counteract.

Neil

[Grunge-Fut]

Tom
PM sent

Steve