Project 1 from EmptyNester. Category: Custom Shop Tools - CNC Table

After using my PP50, I found that my hand isn't nearly as smooth or coordinated as I'd like. So, I'd like to build a CNC table.

Having mostly finisihed the Hovercraft project after a year and a half - I wanted to do something that would be quicker. But, almost any project would be quicker than that! :)

My goal is to do the project for as little money as possible since this is more of a toy than a needed tool. And, to limit initial cash outlay, I wanted to do the project in stages so that I wouldn't have to sink too much money in all at once.

In my work life, I write embedded control software (currently for medical devices), so I'm comfortable with the electronics and software side of the project. I figured I could save the most money on the drive control if I went the E-bay route and I'm fairly confident that if the parts are functional, I'll be able to get them to work.

I have about 8 hours in on the electronics and 8 hours in on the table (just started this week).

I got a four axis drive kit Wantai Motor with:

• (4) Nema 23 428 oz dual shaft motors
• (4) 4.2 ampp stepper controllers
• (2) 36 vokt, 350 watt power supplies
• (1) breakout board
• (1) parallel cable

I didn't necessarily want the dual shaft motors since I don't plan on adding encoders, but this kit shipped from a US warehouse. So, I went with this for $406.

The first thing I did was to do a quick/temporary wiring job to make sure all the components worked. Using the demo version of Mach, I could spin all the motors, so I figured that was good enough to continue with the project. With that done, I picked up my steel on Monday.

I'll post the drawing I did for my table when I get a chance (it's in Visio and I only have that at work).

I'll post pictures and prices since I'm trying to build a "hobby level table" at "garage project prices".

I'll go into more detail on the electronics side, since that information is harder to find when you try to do research on the internet.

There is a free Visio viewer you can use. I use Visio all the time for quick drawings. However, with each new version it seems to be moving more and more away from technical drawings. :( Back from before Microsoft bought it and the was a specific technical edition.

Google sketch up is a good alternative to Visio for this type of drawing, since does dimensional material do well (I.e. lumber, tube, etc.). And it's free to boot!

Cheers
Mike

I now have the table put together and right side up. I still have to weld what was on the under side.

This is only my second big welding project, my welding skill is progressing but I really have a problem with consistency.

Attachment 7376

I'm planning on putting 2" angle around the cutting area so that I can get up to 4" depth for the water table. I have 3" flat stock I'll use for the supports and just put it in notches I'll cut in the angle.

I'm planning on puttiing heavy duty casters on with a leveling foot with each one. That way I can move the table around without help and still be able to get it stationary and level. I kept it low to the ground so I wouldn't have to lift metal as high to get it on the table.

I'm not sure if I'll need to add support in the middle. The inner dimensions of the table are 52" x 76". I expect to lose a couple inches due to carriage dimentions. I assuming I'll have about 50" by 70".

Rege

I got my carriage kit from Precision Plasma ($325). I originally saw it on EBay, but then went to his web site to find out more.

I liked the iPlasma tables he had, but buying a pre-built table wasn't in the budget.

The kit contained the carriage plates and all the bearing and hardware necessary, as well as plans for a portable cutter (just carriage rails, no table).

Attachment 7380Attachment 7381

Two of the completed carriages are below, one X and one Y.

Attachment 7379

Based on the plans that came with the carriage kit, and a discussion with Ron at Precision Plasma, I went with 14 ga 2" square tube for the table and 16 ga 2" stainless for the gantry.

Great start empty
I built a table my self and it was a great project, there is tons of info on the web about CNC tables you may look at CNCzone for one. One thing you need to remember is the size of your water table and the volume of water it will hold and its weight.
Look under hobbyist projects you will find mine (DIY CNC table plasma cutter) and seanMurphy256 posts about builds. PM if you have any questions I will see if I can help.

Have fun
Tom

Quote:

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Originally Posted by acourtjester

Great start empty
One thing you need to remember is the size of your water table and the volume of water it will hold and its weight.

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Tom,

I have seen Sean's, but I'll take a look at yours.

Is there some specific concern about structure and weight of the water? The water weight should be about 400 lbs.

Thanks,
Rege

Just the added weight of the water and the tank needs to be considered when building the table frame. The size of the legs, cross bracing for stability and depth of the water. So guys put chemicals in the water to keep the funk down.

Have fun
tom

Here's the layout for my table. I based this on other tables I had seen and trying to maximize size for materials. I also wanted to not overbuild it so that I could still move it around and handle it while building. (Since this is my first major steel project, I figured the table may be replaced quickly as I learn more. The stainless rails and carriages are the bigger investment and can be reused, if necessary.)

I only have the table about 2' high on purpose. I knew I'd have to lift any steel I want to cut from floor height, so I wanted to minimize the lift distance.

Attachment 7438

Based on recommendations from Ron at Precision Plasma (where I got my carriages) - I'm using 14 ga 2"x2" steel tube for the table and 16 ga 2"x2" stainless tube for the gantry.

The table used:
(2) 2"x2"x24' hot rool
(1) 2"x2"x20' stainless
(1) 2"x2"x1/8" angle (used for the bottom braces between the legs)
(1) 2"x1/8"x20' flat bar
(1) 1 1/2" x 1 1/2" x 1/8" angle
(1) 5' x 8' x 14 ga sheet
(3) 3" x 1/8" flat bar (for support slats)

The flat bar iswelded to the under side of the 2" sq table with 1" protuding toward the center. This gives me a good surface to weld a 14ga steel sheet to for the bottom of the water table.


Table Cutting List - (2) 14 ga 2"x2" square tube
Feet - Inches
6 - 4 table side
6 - 4 table side
6 - 10 center support
2 - 3 mid table support
2 - 0 leg
Total 23 - 9

2 - 3 mid table support
2 - 3 mid table support
2 - 3 mid table support
5 - 4 long end
5 - 0 short end
2 - 0 leg
2 - 0 leg
2 - 0 leg
Total 23 - 1

Leg brace cutting list - (1) 2" x 2" x 1/8 angle
Feet - Inches
6 - 6 table length brace
6 - 6 table length brace
5 - 0 table width brace
5 - 0 table width brace
Total 23 - 0

I also reinforced the corners of the cutting table with 28 1/2" pieces at a 45 degree angle underneath the table on each corner. I used 1 1/2" angle for that.

Corner Brace cutting list - (1) 1 1/2" x 1 1/2" x 1/8 angle
Feet - Inches
2 - 4 corner brace on the bottom of the cutting table
2 - 4 corner brace on the bottom of the cutting table
2 - 4 corner brace on the bottom of the cutting table
2 - 4 corner brace on the bottom of the cutting table
Total 9 - 4


I have basic construction done and have already "learned a lot" (code for "messed it up"). I post some pictures later.

Looking good Nest.

I assume you are going with a gear rack drive for both axis?

What was the cost of teh gantry kit parts? Looks like a pretty nice package.

Thanks.

I did get gear racks for both axis.

The gantry kit was $325. In hindsight, it seems a little steep and I may have gone other directions since I've learned more.

I've had a couple issues with the basic table construction. The first was the inconsistancy of my welds. It took me a while to figure it out, but it turns out that if I'm not sitting or standing upright with a good brace for my hand, my welds suck. But, it's a learning project.

The other problem I've had is that when I put the 2" flat bar on the bottom of the 2" square tube, it cause the tube to bow up (away from the welded side) by 3/4" to and 1" in the middle of the tube. I'm planning on putting a piece of angle on the top of the tube to extend the depth of the water table and to hold the slats. I'm hoping that welding that on will help reduce the bow.

Here's the table as its current state in the garage.

Attachment 7439

I've been going back and forth on how much support is enough for the water table. After talking to my brother in law (long time fitter) and my daughter (materials science engineer doing her post junior year internship in a metalurgy failure analysis lab) - they both think I'll have sufficient support.

The urge is to to support the table bottom more, but with water 3" deep there will be about 400 pounds of water. That's less than 1 pound per square inch. My reasoning (right or wrong) is that the table to leg weld it more of a concern for stress failures than the sheet that is the table bottom.

I'm willing to take a chance. That's the fun part - it's never interesting without the chance of a dramatic failure!

I finished construction of the basic table. I haven't done the mounts for the rails yet.

It has both wheel and anti-vibration feet on it. This will let me move it around the garage by myself. It's worked well for moving it in and out of the garage.

This picture is while I was draining the table after the water test. Unfortunately, I have some work to do on fixing leaks.

Attachment 7598

What was interesting is the two leaks in the photo below. If you look closely, where the arrows are pointing, you can see a gap in the heat affected zone. This is just where the leaks are.

Attachment 7599

For the drain I just used a 1/2" black pipe coupling on the bottom of the water pan and threaded a ball valve on it.

Attachment 7600

Quote:

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Originally Posted by EmptyNester

For the drain I just used a 1/2" black pipe coupling on the bottom of the water pan and threaded a ball valve on it.

Attachment 7600

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May as well put a garden hose adapter on it http://www.amazon.com/Anderson-Metal...094267-8385652 (link is only for illustration)
You could fill it the same way... slowly with no fountain.

I would add some support in the middle, but if you not cutting over 1/4" it will probably work fine.

Quote:

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Originally Posted by SeanMurphy265

I would add some support in the middle, but if you not cutting over 1/4" it will probably work fine.

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I probably won't be doing anything heavy. (I just wouldnt' be able to lift it.) I'm planning on more decorative/artsy stuff.

If you look at post #12 you can see the cross pieces I put in. Would you put in support in addition to that for heaver work?

Zoama,

You've become my idea man! That would work out well for filling and draining.

(I just got the mandrel for my hovercraft muffler. That's was another great idea from you. - Thanks)

That is so not what I meant when I said I wanted a pool table. :D

Quote:

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Originally Posted by Rambozo

That is so not what I meant when I said I wanted a pool table. :D

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Unfortunately, its a little leaky as pools go. I went through one round of patching holes but still have some left.

I probably shouldn't have painted it until after I tested. Now I'm not sure how I'll get the paint out of the corner that needs "patched".

Just get some of that liquid rubber spay they sell on TV. It will fix anything.

Quote:

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Originally Posted by EmptyNester

Unfortunately, its a little leaky as pools go. I went through one round of patching holes but still have some left.

I probably shouldn't have painted it until after I tested. Now I'm not sure how I'll get the paint out of the corner that needs "patched".

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This is true. You also don't know if the paint is sealing other very small leaks. When I used to build oil pans, I found that testing for leaks with solvent or mineral spirits is better than water. Less surface tension and it seems to find everything.
I'm sure a little heat and a wire brush will burn the paint out of your corners enough to re-weld them. MIG and stick can be pretty forgiving about bits of paint, at least. Of course just coating with a sealer is the easy way out.

Quote:

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Originally Posted by EmptyNester

I probably won't be doing anything heavy. (I just wouldnt' be able to lift it.) I'm planning on more decorative/artsy stuff.

If you look at post #12 you can see the cross pieces I put in. Would you put in support in addition to that for heaver work?

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I think it depends on how heavy you go! You have your 4 vertical corner tubes now, but if you add one piece of tube in the middle (vertical) on all four sides that would greatly reduce the capacity of the table. My table is heavier 5'x9' and I used 3/16" and 1/8" tubing; I can slide the table fairly well. I'm going to add some castors in the rear to help move the table.

The main thing that would scare me is the the gantry (depending how you mount it). If you get too much weight on the table it could distort your gantry. I have seen where some people have made their gantry where it could stand alone instead of mounting it to the table.

I called precision plasma about their Z axis and they would not sell me one. Since you bought a kit will they sell you a Z axis?

Quote:

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Originally Posted by SeanMurphy265

I think it depends on how heavy you go! You have your 4 vertical corner tubes now, but if you add one piece of tube in the middle (vertical) on all four sides that would greatly reduce the capacity of the table. My table is heavier 5'x9' and I used 3/16" and 1/8" tubing; I can slide the table fairly well. I'm going to add some castors in the rear to help move the table.

The main thing that would scare me is the the gantry (depending how you mount it). If you get too much weight on the table it could distort your gantry. I have seen where some people have made their gantry where it could stand alone instead of mounting it to the table.

I called precision plasma about their Z axis and they would not sell me one. Since you bought a kit will they sell you a Z axis?

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I had thought about a single leg in the center of the table, but figured that would make wheels much harder. I did figure I could always add legs later and though adding one to the long side of the table would need it first.

I hadn't thought about the weight distorting the gantry. I guess that's something I'll need to keep an eye on.

I didn't pursue buying a z-axis from precision plasma. They seemed too expensive and were beyond my budget. I got one from No Sleep Studio. In hind sight, I may have gone with their gantry kit had I known about them at the time I purchased my kit.

It's funny that they wouldn't sell to you. I had a similar thing happen with C and CNC. I sent him questions about his low cost THC. I figured that was the best for the money. I asked if he had experience with Everlast machines. He told me a Longevity machine blew up one of his boards. He then said that since they are from China and Everlast is from China - I wouldn't get a warranty. After that, he didn't response to email.

As a result of that, I'm going to try using an Arduino board to make a THC. I have the board with a display (about $45) and am adding a prototype board ($12). I think I'll need about $10 to $20 worth of parts. I write embedded control software for a living, so I don't think that will be a challenge. The only hard part will be discovering all the "gotcha's" a THC has to deal with.

So, when I get it "mostly working" - I'll make it open source for anyone who wants to use it.

Since I have a sqaure tube frame, I decided to use angle to make an adjustable mount for the gantry rail.

I cut a wood pattern so that I could cut slots in the angle. It would allow bolting the angle to the square tube legs. The slots are vertical so that the entire piece of angle can be moved up and down to level the gantry rails to each other.

At the top of the angle, I put another piece that had a slot in it. This is to allow movement of the gantry rail closer and further in relation to the other side.

Attachment 7705

I've had the drive electronics set up for a while. I just hadn't gotten around to taking any pictures to post.

I used an old PC case to house everything. I had thought about using the power supply in it for 5V and 12V, but decided it was too big and too much of a pain since it needed the power control logic overridden (no PC to power it on and off).

This is a 4 axis kit from ebay. It came with two power supplies for the motors. They are mounted on the top and bottom of the case. I arranged them so that one of the x-axis motors was on each power supply. It seems like it would balance the load a little better.

Attachment 7707

I mounted the four motor controllers in the middle.

I left the original PC fan in. I got a small 12V power supply (upper left corner) to run the fan. I have additional fans and will add them if necessary.

Right under the fan is the break out board. I have it mounted so the parallel port connecter goes out an existing hole in the case.

I have a five volt power supply (again, from e-bay) mounted in one of the drive bays. It's used to run the logic voltage on the stepper motors and the motor side of the break out board.

I decided to use isolated power supplies for the BOB. I had an old 5V wall wart from an iPod, so I used that for the PC side of the BOB.

I couldn't find any reasonably priced connectors that I liked for the drive cables. So, I went the cheap route and got a couple terminal strips. Given that I'm not going to be taking everything apart often, I think that will be fine.

Attachment 7706

I've already had it all running the motors. That was the first thing I did when I got the kit. They had a 14 day return period, so I wanted to make sure that they worked.

I cut the slats and put them in the table.

Attachment 7714

I had orginally put in slots every six inches. When I looked at it, I decided that was too far apart. So, I went to four inch slots. As a result, I didn't have enough steel to fill them all.

I just painted the gantry rail mounts, so I'll be able to mount them and the gantry rails in a couple days.


Question:
I had been thinking of painting the slats with heat resistant paint. Anyone have any experience with that? Is it a good or bad idea?

Got the gantry rail adjusters and gantry rail installed. All the adjustments went well and it was easy to get everything square and level.

Attachment 7729

Got the gear racks installed. Then did a third water test after using the leveling feet to set the table up. (Y-axis is just siting there, its not finished.)

Leveling feet worked great. Only one small leak left in a corner. I'm not sure if I should use silicone caulking or the spray on rubber sealant. (The leak was in a tube joint and water was going into the frame tube and coming out a pinhole in the bottom weld. I drilled a drain hole in the bottom of the tube so that water wouldn't accumulate.)

Attachment 7757

Because of concern that I might need additional support in the middle of the table, I took measurements before filling with water and after. There was absolutely no deflection. I didn't have the slats or any material to be cut loaded, but I did overfill it with water. So, I'll probably test it again with slats and steel to be cut, but I'm thinking it will be okay without additional feet.

Looks really nice. I'm really liking the low deck height, I can just imagine how much easier it will be to load. I wonder if anyone has built one at pallet jack height.
I'm sure any minor deflection will be taken care of by the torch height control. As long as your axis run true and do not contaminate each other a little Z error should be no big deal for plasma. If you also want to mount a router, you might have to be a little more precise. Since you have everything adjustable, I'm sure you can get it all dialed in.
Have you taken any measurements to see how true your rails are? I know square tube isn't as close as DOM, but I don't know how much different. Did you measure your rails to use the best sides for the most critical axis?

Thanks.

I did the "stack the tubes and look for warpage". They looked fine.

I also measured the distnace between the rails in a couple places along the length when I put them on the table. They seemed very good. But I probably need to start derating my eyes for measurement accuracy:) If they are off, it's under 1/16th (probably my current eyeball accuracy).

I only did height at the ends, but should probably do that along the length.

I'm not sure I understand the "measure the rails to use the best sides for the critial axis"?

Long term, I am hoping to make a router mount. I've seen some pictures of steel inlaid in a table top. I really like it and figured that would be a good use of a router.

I meant with a straight edge and dial indicator. One of the nice things about a gantry design, is that you can use parts of it to check other parts. By only mounting your crossbar at one end you can put an indicator on the other and adjust your rails to have minimum runout all along them. You will also know how parallel they are and how much deflection there will be. Since things won't be perfect, you probably want to set your X rails so that the straightest sides guide Y. And setup Y so that there is minimal runout in X. This will put the bulk of your error into the Z axis which the THC can take care of. A lot depends on the final accuracy you are looking for. If you plan to do router engraving, the Z will need to as accurate as you can make it. V groove bits are not forgiving at shallow cuts. I would say plus or minus .005" or less would be ideal. Obviously for plasma you don't need to be anywhere near that close.

One nice thing about modern software is that it can compensate for a lot of error in the hardware. I know there are tools to map the periodic error in gears and gear rack, then you tell your control software and from then on it will automatically adjust so that it looks like you have a perfect gear system with zero error.

I was looking at your carriages and they are almost exactly like the ones I purchased from No Sleep Studio. I think the guy from PP called out the guy at No Sleep Studio on CNC Zone for making his kit very similar to PP. Is this kit the same as their Iplasma? Have you kept up with how much you have spent?

Quote:

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Originally Posted by SeanMurphy265

I was looking at your carriages and they are almost exactly like the ones I purchased from No Sleep Studio. I think the guy from PP called out the guy at No Sleep Studio on CNC Zone for making his kit very similar to PP. Is this kit the same as their Iplasma? Have you kept up with how much you have spent?

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It's funny for calling someone out on a simple carriage design like that. I would bet that's a pretty common design approach. Sadly, they are different enough that my NoSleep Z-axis mounting holes don't match those on the PP carriage.

The guy at PP said they don't make any tables with that carriage any more because it is the least precise and the rails need to be kept clean. I did think the price was a little high ($325), but the hovercraft project taught me that its worth paying more for a kit so you have somebody you can call if you need to. (But in hindsight, I might have gone with the NoSleep gantry had I known about it at the time.)

I have kept track of the spend. I haven't totalled it lately but will post a total cost and parts list. It was a mixed bag of spending more or less than expected, but I think I'm still coming out significantly less expensive than buying. The biggest costs were $325 for the gantry, about $450 for steel (including water table) and $400 for motors/drivers/power supplies (I don't recall the cost of the cabling and gear and racks).

When I welded the carriage, I didn't think about the cross tube between the two x-axis.

I ran a weld bead along both the top and bottom of each joint. The top of the top joint is where the y-axis bolts on. The weld bead would have prevented any adjustment in length of the y-axis (it's a slotted plate).

Attachment 7772

A little bit of grinding and the situation was fixed.

So, I updated the spreadsheet I'm using to track cost with. I think (hope) this will be my final cost. I tried to format it in a table, but all the spacing keeps getting deleted.

The quick summary is:
- my table and electronics $1972 (versus $4305 - purchasing system)
- z-axis and floating head $337
- Mach3 and Sheetcam $325

Grand Total - $2634 (versus $4967 grand total for commerical system)


Here's a breakdown of what I paid for stuff........

Stuff I didn't buy
PC - Had an old one
Case for electronics - Used an older PC case
misc nuts/bolts

Stuff I bought (for a 4' x 6' table)


Precision Plasma Carriage Kit $325.00
Steel Frame $365.00
Steel Water Pan (not stainless) $120.00
McMaster (3) 6' Racks $162.00
McMaster (4) Gears $62.00
McMaster Flex Cable $50.00
McMaster VHB Tape $23.00
McMaster (4) Anti-vib leveling feet $30.00
Table Total $1,137.0

Motor Drive/Electronics Total
Ebay 4 Axis Control (428 oz motors) $407.00
Ebay 5 Volt supply $17.00
Ebay 12 volt power supply $7.00
Ebay Relay card $3.00
ebay Limit Switches (12) $10.00
ebay E-stop switch (4) $16.00
ebay Arduino for THC $24.00
Amazon Terminal strips $14.00
Motor Drive Total $498.00

My Total 4'x6' Table & Electronics $1,972.0

Comparision 4x4 iPlasma w/ stainless pan $2,995.0
C and CNC motors (300 oz) $1,310.0
total w/o Z-axis mechanicals $4,305.0



Additional Stuff you'd buy either way

Z-Axis
McMaster Torch attach collar $7.00
No Sleep Studio Z-axis, floating plate $330.00
Z-axis total $337.00

Software
www.Artsoft.com Mach3 $175.00
sheetcam.com Sheetcam TNG $150.00
Software Total $325.00

I have the Precision Plasma carriage kit and the ShopDroids Z-Axis. The mounting holes didn't match.

I had to drill new holes on the carriage. ShopDroids sent me spacers so that the bearing bolt head wasn't an issue.

Attachment 7791 Attachment 7792

I also have the touch and go plate, but couldn't install it because I forgot to order the bushings for it.

Do you think the Z axis is strong enough for a router? I've thought about making a separate plate with mounts that would hold a dremel for cutting designs from 4x8 sheets of foam.

Quote:

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Originally Posted by SeanMurphy265

Do you think the Z axis is strong enough for a router? I've thought about making a separate plate with mounts that would hold a dremel for cutting designs from 4x8 sheets of foam.

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On the No Sleep Studio web site, they have a video showing different weights being hung off the axis. I don't recall what the most weighed, but it seemed significantly more than a router. Just based on the weight of everything, I would think flexing of the z-axis would be the biggest issue.

I've seen aluminum mounting brackets on e-bay for routers. I figured I would just go that path and mount it directly to the aluminum frame of the z-axis. I would be buying a router motor for it too, but figured I'd wait until the Plasma was fully up and running.

One of the things I've seen that I think was really cool was a table that had plasma cut steel on the top and was covered in glass. With the router, it could be done as an inlay.

While waiting for the Y-axis I made a shelf to hold my PC, drive electronics and PP50. I got a used shipping crate I got at work. I cut it in half and then just put it on a ripped 2x4's that went the width of the table.

Just got the gantry cross tube back. I haven't put the track on it yet, but put it in place so I could start hooking up the drive electronics to start playing with them.

The first thing I did was install the E-stop. Since the switches were cheap and I'll be using the table where I may have trouble moving around it fast - I decided to put an e-stop switch on each side of the table. I mounted them in caps that go on the 2" square tube.

After finishing that, I started running the first wire for the motors. I immediately saw that having an e-stop on the side with the cables won't work.

Attachment 7806

Since that's the side that will have the PC on it - I'll just ditch that e-stop.

I also worked on the menu system for the THC. I have the top level menu working. When I finish all of it, I'll post a video on the Plasma thread that talks about it.

I started final assembly of everything.

Attachment 7838
The X axis is fine and seems pretty smooth (only have 1 motor moutned on it currently).

I'm having trouble with the Y-axis. It will bind as I run it along the tube. When it binds the bottom of the vertical piece of the carriage seems to kick out from the tube.

Attachment 7839

I did a quick check and it appears that the top and bottom plate are much closer than the x-axis carriages. Around 1/10" on the side you see in the picture. I'm surprised I didn't see it sooner.

I'm guessing that the dimension is the cause of my problem, so I'll have to figure out how to fix it.