New member, sweet find at the auction, and a massive gantry

[Simko]

Hello everyone... This is my first post on the forum. I live in the US, more specifically in Pennsylvania. I am an electrical engineer by schooling (Penn State), but rarely get to use it in my current job as a manager of engineering and maintenance.

I have been researching for a while on building some sort of CNC machine (mini-mill, 3d-printer, plasma table, etc). I decided definitely that a plasma table would be a great project as well as a useful tool in my 40x64 home shop.

I originally started down the path of buying a Precision Plasma gantry, building my own frame, and outfitting the table with controls from CandCNC, and using Mach 3/SheetCAM as the software.

Luck would have it that I stumbled upon what I thought would make a great platform for a CNC plasma table. I picked it up at an auction for $200. It is a 5'x10' table that was used to measure hole locations in large wood panels. The gantry was manually moved and a tapered probe was placed in each hole and a location was sent to a computer where it compared the results to a blueprint. Each axis runs on linear bearings and each axis is also outfitted with DRO scales. I would need to add some sort of hardware to move the gantry automatically: rack/pinion, ballscrews, etc.

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Now that I have read more and I am starting to understand the process a little better, I am questioning if I will be able to use the table in it's current state due to the weight of the gantry. The side plates are 1/2" steel and the crossmember is structural steel tubing of an unknown thickness (just need to take out a bolt and make a measurement). Even with how heavy the gantry looks, it slides incredibly easy on the linear bearings with fingertip pressure.

Is it worth going down the path to get this machine going as is or will I have issues with accel/decel of the gantry when making fast cuts in thin material. Even though it moves easily, I am worried that it won't change directions quickly due to the gantry weight.

Any insight would be appreciated as well as links to information on calculating motor size, rack/pinion size, etc in relation to gantry weight.

Thanks and I look forward to posting more on the forum.

- Steve

[acourtjester]

I think that if you have the room for this table it is a great start. I do not see any motors did you get any electronics with the table??
One thing is the height of the Y axis you many need to cut it off and put some extensions to get it higher for using it as a plasma table.
Or if you can remove the table top and drop it down that may be the way to go for that. That looks like a commercial router table I worked on for a guy here in town. You will need 4 motors 2 for the X axis (one on each side). A PC and control electronics, power supplies and motors you will be ready to make it move.

have fun
Tom

[chattacuda]

Just my 2 cents. First of all, the table is a great find. I am sure you can use the two long rails. If it were mine, i would build a water table to fit your frame and buy a new lighter weight gantry. It takes some hefty electronics and motors to accelerate a heavy gantry at the speeds needed for plasma cutting thinner stuff, and especially aluminum. I would suggest contacting precision plasma and getting the parts to make a 5' gantry to fit your rails and get hold of CandCNC for the electronics. I am very pleased with both of their products and customer support.

[Capstone]

just for the structure alone, the table is worth 4x that. But here's the best advise I can offer.

Ask yourself a few questions right off..

1. Your temperament; Are you going to be able to keep your sanity when this project drives you nuts? because it will. trust me. If you are not able to handle frustration well or just don't need the aggravation, run, don't walk, to the scrap yard. The $200 and a giant piece of headache will be out of your life.
3. Budget.. you could easily take that skeleton and retro-fit this top to a workhorse with production capable motors/electronics and go to town, but what's your actual budget overall, because you could easily spend more than a turn-key solution would cost and avoid most of question 1 or you could accept your fate and spend just as much on the trial and error and experience. your choice, either way, you'll spend more than you planned, bet on it.

Now, read question 1 again, just to make sure.

3. Primary purpose of table? Plasma only, dual purpose? Thin artsy stuff mostly or fab thick stuff or both?
Lastly, read question 1 again, just to make sure.

Made it this far.. ok, don't spend another penny on the hardware until you've spent a few weeks checking out all the cool stuff you can make and play with all of the free apps to learn how to design your own stuff and go to youtube and watch about 20 hours of videos, then read about all of the headaches everyone here goes through to fix every little crazy thing that can go wrong and after two weeks, come back to this thread and read question one again. If you're answer is still yes... quote my post here and say, "I'm ready and accept that I am about to test the limits of my sanity " and we'll all collectively give you enough info to make this as painless as possible.

Or do what I did... and charge right in, spend 4x more than needed, get the satisfaction of doing most of it myself, with help from some great people here and after 3 years still wake up half nuts thinking about something to be done in the garage.

Phil

[steel 35]

That looks like a commercial router table

have fun
Tom

And that's where I would be leaning! Oh wait it already is.

[Simko]

Thanks for all the fast replies!

I am looking to do mostly thicker fab stuff, but I definitely want to be able to do the artsy stuff as needed. My friends and I are in to building off-road Jeeps and always need some sort of bracket, tab, or gusset made up. I also live in a very remote area where there is plenty of oil drilling and fracking being done. I am hoping to be able to make pieces parts for their operations as well as for other industrial customers in the area.

After the table is functioning properly, I would like to be able to add routing capability for materials such as wood, phenolic, UHMW, and other plastics.

I have 15+ years of experience with different software including AutoCAD, Corel Draw, Adobe Illustrator, etc.

I also have a small 12" vinyl cutter that I have been running for 14 years so I am fairly familiar with how to convert pictures, bmps, etc into a cut-able vector format. CorelTrace works really good but takes some trial and error with resizing the image to get a good smooth trace.

My budget is around $10k, for a complete working table with Hypertherm 65. The wife would like the budget to be lower though...

I am tending to agree with you guys that the gantry is probably too heavy. I like the idea of asking Precision Plasma is they could make a semi-custom gantry to fit the width of my liner rails and then just mount the liner bearing block to their gantry and not use their bearing system.

I think that I can sell some of the other pieces off of the table to help fund the project. The 5' and 10' glass digital-read-out scales/readers have to be worth something to someone with a large scale milling table.

Capstone... I accept your challenge. I commute 3 hours per day and have been listening to YouTube videos for the last few days on different plasma topics. The problem is that 75% of the videos are just people showing their table making cuts with no voice-over describing what they are doing.

Ok.... I'm off to do my homework!

[Joe Jones]

Damn! That would make one Hell of a nice Samson 510 CNC ROUTER table! The table surface perfectly flat, and SOLID. I wish I knew about that sale. I would have bought that in a heartbeat, and mounted the Samson 510 rails and gantry above the table to give me the functionality of the Samson table with the stability of that MONSTER base!

What does that table WEIGH???

If you want to sell it to recover your $200, I'll buy it, and I will come up from Kentucky to pick it up!

[suttoncnc]

All I can say is WOW!!!!!!!!

I wish that I could find something like that for $200.00. The possibilities for a very serious industrial grade CNC router are written all over that thing. I would not even think about a Plasma machine for that setup.

[Thor]

As someone who built a heavier gantry machine, that looks like a great starting point. Forget a little bit of the wieght of the gantry for a bit. First it will more than likely need to be raised for good clearance and keep water splash off the cross rail bearing. Second from what I can tell it looks to be a tall gantry beam but not very deep. This is where you'll have problems at higher speeds, the tube will bounce to much front to back as thats where the accel/decel hits it, up down is very little as the torch can move slower and only weighs a little bit.

So taking both those things into consideration, plan on redoing the gantry tube.you very well might be able to reuse the rail and scale, and maybe even the tube itself just layed over 90 deg from where it is and then remount the rail on the front. Or build the gantry from scratch or PP parts and see if you can still reuse the rail and scale.

If the gantry is strong then all that the weight makes a difference on is the size and type of motors it gets driven with. My gantry probably weighs well over 300 lbs but I can zip it up to 1400 ipm rapid travel no problem with dual 750 watt ac servos, I had to slow my accel rate down as even a 12" aluminum channel still wants to flop around in the middle at high rates, but I'm still at a higher rate than alot of stepper built machines (like my accel rates were at about 100 in per s/s, had to slow down to 75 for better high speed cuts)

[Simko]

I haven't done much with the table. In fact, I still haven't trailered it to my shop yet. My plan is to put the table to the right of the overhead door at the back of the building under the stairs. If the building looks pretty plain inside right now, it's because the wife and I just recently finished sheeting and painting the walls along with running lights and receptacles. Now it's time to fill it up.... I have been slowly moving all of my stuff in from the other garage.

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I also picked up a MIG and TIG welder at auction. The MIG is a Hobart BetaMig 251 and the TIG is a Lincoln IdealArc 300/300. The Lincoln looked pretty rough so I stripped it down, gave it a fresh coat of paint, and make some stickers for it on the vinyl cutter.

TIG.jpg

Finally, I got an old 1.8Ghz AMD computer set up with a fresh install of XP and Mach 3. I took some old DVD-roms apart for the 4-wire stepper motors and ordered a cheap Chinese 3-axis driver from Ebay to play with on my desktop to get a better understanding of how to configure and program Mach 3.

Things are coming together... My biggest decision right now is to keep the heavy gantry and put robust motors on it, or redo the gantry completely and put more standard sized motors on it. Originally I thought that going with a Precision Plasma gantry would be the ticket, but their website says specifically that they will not make any custom gantries. The next option would be to buy parts from CNC Router Parts to make a new one.

[Simko]

I'm picking up the table this Friday!

First order of business is to get a weight on the gantry and make a decision on if Nema 34 motors will drive it adequately and with what ratio of reduction.

Are there any calculators or equations out there to check rpms, cut speed, g's, etc based on the gantry weight.

[_Ogre]

i think you have a good base to start a plasma table. talk with matt over at starlabs (bulltear) and buy a light weight gantry kit with motors. he will probably need to know exactly how wide the linear rails are so he can make the gantry the correct width. i'd stay with candcnc controls like starlabs sells just for the support available

[Capstone]

I'm picking up the table this Friday!

First order of business is to get a weight on the gantry and make a decision on if Nema 34 motors will drive it adequately and with what ratio of reduction.

Are there any calculators or equations out there to check rpms, cut speed, g's, etc based on the gantry weight.

C&CNC can definitely help you determine the load requirements, but I suspect you might have to use servos, not steppers.

[Simko]

I got the table home and unloaded. It took about 3 hours, two 35HP tractors, and we almost rolled both tractors twice! I can't believe how heavy this table is.

trailer.jpg

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The frame under the table is 6"x6"x1/4" angle, the whole table is criss-crossed underneath with 6"x1/4" bar gussets. The entire 6'x10' top surface of the table is 3/4" BLANCHARD GROUND steel plate.

gussets.jpg

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I took the gantry off before unloading because it was so heavy that we couldn't pick up that side of the table with the tractor. The gantry is 4"x6"x1/4" structural steel with 1/2" steel end-plates. The bearing system is an NSK LS25 rail with two trucks on each side.

bearings.jpg

I think at this point, I am going to scrap the idea of using the existing gantry. It is just WAY TOO heavy.

Also, my original plan was to cut out the white portion of the table top, but at this point, I think that is a crazy idea. I am leaning more towards building a tray on top of the table.

I would really like to end up with a down-draft system versus a water table.

Is it possible to make a 'tray' into a downdraft system?

[Simko]

Made it this far.. ok, don't spend another penny on the hardware until you've spent a few weeks checking out all the cool stuff you can make and play with all of the free apps to learn how to design your own stuff and go to youtube and watch about 20 hours of videos, then read about all of the headaches everyone here goes through to fix every little crazy thing that can go wrong and after two weeks, come back to this thread and read question one again. If you're answer is still yes... quote my post here and say, "I'm ready and accept that I am about to test the limits of my sanity " and we'll all collectively give you enough info to make this as painless as possible.

"I'm ready and accept that I am about to test the limits of my sanity "

[Capstone]

Made it this far.. ok, don't spend another penny on the hardware until you've spent a few weeks checking out all the cool stuff you can make and play with all of the free apps to learn how to design your own stuff and go to youtube and watch about 20 hours of videos, then read about all of the headaches everyone here goes through to fix every little crazy thing that can go wrong and after two weeks, come back to this thread and read question one again. If you're answer is still yes... quote my post here and say, "I'm ready and accept that I am about to test the limits of my sanity " and we'll all collectively give you enough info to make this as painless as possible.

"I'm ready and accept that I am about to test the limits of my sanity "

Alrighty then!

[Capstone]

I think at this point, I am going to scrap the idea of using the existing gantry. It is just WAY TOO heavy.

Also, my original plan was to cut out the white portion of the table top, but at this point, I think that is a crazy idea. I am leaning more towards building a tray on top of the table.

I would really like to end up with a down-draft system versus a water table.

Is it possible to make a 'tray' into a downdraft system?

I would do a simple cost benefit or pros and cons listing between a water table or downdraft. There's actually two other choices. A combo of both or nothing at all, just a mesh/grid similar to a plasmacam.

Keith Fenner went with the a downdraft and watertable on his plasmacam, but still uses the default wide pointy slates. You'll have to search through a lot of his videos to see the progress/upgrades, but he's pretty thorough with his explanations and reasons.

I think if there was a poll, most would say they have watertables and are happy, but it's definitely not without it's issues

I have a watertable, but still use cross fans to eliminate the smoke. It's not ideal, but at least I don't have to wear a mask while cutting. The dust still gets everywhere, cruddy water splashes everywhere and I constantly have to sweep up to keep the stuff from getting tracked into my house.

I'm sure others can weigh in on their experiences, but if you're in tight quarters, you'll want to dedicate a good sized budget for both measures or plan to make changes/upgrades along the way.

[Simko]

I drew up my table in Inventor so that I would have a way to try out different gantry and tray heights to see how they will work out along with the Hypertherm machine torch.

Does anyone know where I might find a CAD model of the Hypertherm machine torch or at least some decent dimensions so I can draw one up and add it to the model once I put the z-axis on it.

table1.jpg

table2.jpg

[jimcolt]

Which Hypertherm machine torch?

Jim colt Hypertherm

[Simko]

I am still deciding between the 65 and 85, but will most likely end up with the 65 to start with (unless there are compelling reasons to make the jump to an 85 or larger).

[Simko]

Jim... Any luck on a model for the PM65 or PM85 torch?

If not, does anyone have some rough dimensions on the machine torches?

Also.. I ordered my first piece for the table today. I got an 8'-6" piece of 8016 extrusion for my gantry. I only need 6'-6", but the price was right. I got it for $190. The 80/20 store on EBay has them for $350 and the guy that I bought it from has them on sale (normally $250). Anyways, if you are looking for a beefy aluminum extrusion for a gantry, I don't think you can go wrong with the price. Plus it is 80/20 brand, not some China extrusion.

Next on the list to order is gear rack, belt reduction, z-axis...

[acourtjester]

buy this kit as it has both hand a machine torch at a very goo price.
Hypertherm Powermax 65 with 75° Hand Torch / 180° Machine Torch 083300
The Duramax machine torch is 1.375" in diameter and about 15" long

[Simko]

Thanks.. I didn't realize they had one with both torches included!

[Simko]

10" deep 'tray' on top of the existing table that will become a combination water/draft table. The plan is to make the tray in two pieces and have a duct connected to each zone at the ends of the table. The slats are going to be arranged so that they allow airflow towards the ends of the table. The bottom 2" of the tray will be filled with water about 8" below the cut surface.

There is 9" of space between the top of the tray and the bottom of the gantry which I am hoping gives me plenty of space for a rotary cutter and for cutting large pieces.

I am not keen on my arrangement of the linear rail to the gear rack, but the linear rail was already installed on the table when I bought it and I hate to move it and have to drill/tap 60 holes if I can make it work as is.

table.jpg

[SolarImages]

I have been designing/building a cnc machine or two for the last two years. I certainly have been looking at what you are looking at right now for the last two years. I have a old Dynacnc 11' x 6' table while they are great due to all the extrusion stuff being readily available for modification there fail point for me was the single Y gantry drive motor so redesign rebuild here we go. I would in your case look at extending the verticle extrusion down to the Linear bearing plate to reduce movement from quick corners. A full verticle piece of extrusion from bearing blocks to Horizontal Gantry will serve you way better here. As well you will lose some long travel but the higher the gantry needs to be the wider the distance between the linear bearings need to be i would suggest using some more 8020 and mounting them 10" apart teeing up to the gantry from that. Also if you have not made the riser box you have drawn the lower you keep the gantry the better. and as far as the water/air down draft table from what i have looked into for the the last two years i think if you mimic a down draft sanding table made from steel of course you won't need water (FYI no expert here). Just my two cents in progress cheers!