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View Full Version : Tig weld rack and pinion to cnc plasma frame?



warwick
17-11-2016, 05:47 PM
hi, im building a cnc plasma table, its constructed from 80x80x6 box section, with 80x80xx6 angle running along side the y axis to support the linier rails.....

im using rack gear system to drive it.....

Can i tig the rack onto the angle rather than drill and tapping? also, i want the x gantry to be able to extend outside the table so i can cut large diamiter pipe.i was thinking of using a piece of link pallet racking to make the gantry,it being light and strong

Lee Roberts
17-11-2016, 08:44 PM
Looking at the pictures of what you've built so far, I think you probably already know the answer to the "welding rack to frame" question?

Surly the rack is far to precious to weld it in place?
What about distortion from the heat build up?
Would the tempering of the steel be effected from welding it in place?

Will you need any adjustment/wiggle room from the rack, when it comes to truing everything up and final assembly ?

Not sure I would risk it myself and just bolt, shouldn't take that much longer.

Nice work so far by the way, it's looking good, start a build log!

JAZZCNC
17-11-2016, 08:44 PM
Lazy bugger get the drill out. . Lol . . . . I've recently done exactly same thing on Router but used Nut bolts didn't tap and didn't take that long really. (My rack was pre drilled thou)

Tig will work but for the little extra work I'd be inclined to Drill.


On another note I noticed in another thread you mentioned no CNC experience. Let me warn you now that Plasma requires that your electrical side is done correctly otherwise you'll have nothing but issues from electrical noise coming from the plasma.
The mechanical side is fairly simple and relatively light weight so don't need massive power or build but the electrical side needs to be Rock solid.

warwick
17-11-2016, 10:15 PM
Lazy bugger get the drill out. . Lol . . . . I've recently done exactly same thing on Router but used Nut bolts didn't tap and didn't take that long really. (My rack was pre drilled thou)

Tig will work but for the little extra work I'd be inclined to Drill.


On another note I noticed in another thread you mentioned no CNC experience. Let me warn you now that Plasma requires that your electrical side is done correctly otherwise you'll have nothing but issues from electrical noise coming from the plasma.
The mechanical side is fairly simple and relatively light weight so don't need massive power or build but the electrical side needs to be Rock solid.

i thought id cut a few corners previously and bought a project cnc plasma off a well known auction site..iv junked it all apart from the longest linier rails which im going to use for my x axis on this one.....im using 4nm nema 23's...Stepper Motor Driver 6.0A, 80V CNC Microstepping CW8060 .....Breakout board CP0-10V CNC 4 Axis with Charge Pump and Relay ....600W PSU 48V 12A CNC Power Supply Stepper Motor Milling ........EMI Panel Mount IEC Filter 10A ......UC100 USB Motion Controller ...and a thc 150 proma elektron
....iv got some help off someone local to me for the wiring and setting up.....iv built the ttable as heavy as possible but id like the gantry to be light and as rigid as possible

JAZZCNC
17-11-2016, 10:50 PM
USB could be problem.? It's flakey and not very good with noise. If you can afford it then I would look at controller with Ethernet.

Cslabs Ip-m is excellent industrial strength controller with 24V I/O which is very noise immune. It can also be used for THC.
It does allow slaved motors with one slight draw back that it only homes to one switch for slaved axis but for Plasma machine this isn't really big deal.

I fit these all the time and tell you 100% confidence nothing comes close to it for reliabilty and noise immunity. It's the Only controller I've used that will allow me to weld with TIG next to machine and not stop it.! . . . . I've used most controllers and none have been able to handle Tig at close range or on same Ring.

warwick
18-11-2016, 03:14 AM
the machine is getting built so another controller at the end i will run to if it makes it work reliably, iv ordered and had delivered 16mm supported linear rails 3200mm..iv unpacked them tonight and the look really weedy...i was thinking of using a piece of 80x80 box to make the gantry or a piece of link pallet racking (doesnt seem such a great idea now)...whats the best way to construct a light weight gantry? i have linear rails and 2m of r&p...im worried that the y axis rails arnt going to stand the weight and forces??

i want the gantry to pertrude past the y axis outside the table and be able to run an ingraver...im not ever planning on doing any milling on this machine...iv got alot riding on this plasma working and working well,any help will be very greatfully receaved

Clive S
18-11-2016, 09:11 AM
i want the gantry to pertrude past the y axis outside the table and be able to run an ingraver.Not sure that this will be a good idea. How are you going to implement it?

JAZZCNC
18-11-2016, 01:28 PM
16mm supported rails will handle 80mm box section easily so wouldn't be bothered there.

Dump the link pallet idea as it will only cause you grief. No point spoiling machine for little extra piece of box section costs.
80mm or 100mm box with with few well placed braces will be fine for plasma machine.
Regards the overhang then if you talking about using for Rotary type axis hanging off the side then yes no problem.

But if your talking about actually engraving on separate table kind of thing then I'd say don't waste your time and just build another machine because engraver and plasma are two very different animals.
Engraving machine needs to be far stiffer and accurate to work well and R&P just isn't going to cut if any real fine engraving type work is to be done.

warwick
18-11-2016, 03:19 PM
Not sure that this will be a good idea. How are you going to implement it?
hi clive, i'll be extending the gantry outpast the side of the machine so i can carve gas cylinders19644


16mm supported rails will handle 80mm box section easily so wouldn't be bothered there.

Dump the link pallet idea as it will only cause you grief. No point spoiling machine for little extra piece of box section costs.
80mm or 100mm box with with few well placed braces will be fine for plasma machine.
Regards the overhang then if you talking about using for Rotary type axis hanging off the side then yes no problem.

But if your talking about actually engraving on separate table kind of thing then I'd say don't waste your time and just build another machine because engraver and plasma are two very different animals.
Engraving machine needs to be far stiffer and accurate to work well and R&P just isn't going to cut if any real fine engraving type work is to be done.

i'd like to be able to cut gas cylinder up,so i thought a couple of pillow block bearing supporting a shaft and then geared down so i can drive it with a stepper motor (in very simple terms):cheerful:.........you say 80x80 or 100x100 box will be ok..do you mean mild steel box or alloy? im more comfortable working in steel ..the link pallet racking idea was just because i had a pallet of the stuff knocking around BUT as youve said it will just devalue the integrety of the machine ...many thanks....

Clive S
18-11-2016, 04:20 PM
i'll be extending the gantry outpast the side of the machine so i can carve gas cylindersJust for clarity do you mean carve or cut with plasma by rotating the cylinder?

warwick
18-11-2016, 04:50 PM
Just for clarity do you mean carve or cut with plasma by rotating the cylinder?

very sorry...i would like to cut with the plasma.......................

Clive S
18-11-2016, 05:23 PM
very sorry...i would like to cut with the plasma.......................Well in that case I think it would be fine.

JAZZCNC
18-11-2016, 06:18 PM
There's better way to do this than having wide gantry making for large foot print if only want to cut cylinders which are less than width of machine.?

Make the Top rails longer so gantry over hangs the end. I do this with routers so 4th axis can be added or Panels cut on there ends. IE: Hindges or Dovetails etc. Take less space and easy to do.

warwick
18-11-2016, 06:29 PM
There's better way to do this than having wide gantry making for large foot print if only want to cut cylinders which are less than width of machine.?

Make the Top rails longer so gantry over hangs the end. I do this with routers so 4th axis can be added or Panels cut on there ends. IE: Hindges or Dovetails etc. Take less space and easy to do.

that was my initial thinking,but the y axis is 3m long and the longest rails i could find were the 16mm supported rail that are 3.2m ...i have 2m of r&p spare and some long lengths supported rail so i figured the only option was to side mount.....i would like to be able to get the x axis gantry completely out of the way so i can load an 8x4 sheets on my own with out to much worry of damage to the machine......the size of the machine and space isnt an issue where we are for now......id like to have an engraver along side the plasma torch so i can scribe parts for folding and numbering etc.is this going to be possible???

JAZZCNC
18-11-2016, 06:58 PM
Marking and scribing etc will be no problem provided you have enough resolution. What kind of ratio and pinion size are you thinking to use.

warwick
18-11-2016, 07:11 PM
Marking and scribing etc will be no problem provided you have enough resolution. What kind of ratio and pinion size are you thinking to use.

think the pinions are 20t and was hoping to use a 60t for 3/1 gearing....as for resolution i havent a clue as of yet..have just been taking advice from a very nice fella locally and building it in stages..right at the start of my craving for cnc i was totally over whelmed so now im just doing stages and moving to the next part of the build....

JAZZCNC
18-11-2016, 08:00 PM
think the pinions are 20t and was hoping to use a 60t for 3/1 gearing....as for resolution i havent a clue as of yet..have just been taking advice from a very nice fella locally and building it in stages..right at the start of my craving for cnc i was totally over whelmed so now im just doing stages and moving to the next part of the build....

Ok well lets work it out for you. I'll assume Mod1 pinion. So the Diametric pitch (basicly diameter) will be 20mm because Mod1 =1mm times the #teeth.
Apply \pi and the affective pitch is 62.832mm which is huge and why you need ratio. So then divided by the ratio to give pitch of 20.95mm per rev.

Working on motors full step value then Full step resolution will be 20.95/200=0.104mm per Step.

Now this is the smallest amount you'll move if the drives where set to Full step. Which you won't want to do otherwsie they'll run like bag of marbles. But take it thats your worst case scenerio.
In real use you'll have the drives set to something like 800 or 1600 micro steps. Going above this is pretty much wasted and just stress the system for very little gain.

So Best case will 20.95 / 1600 = 0.013mm thou don't get excited because you won't get that in reality but will fall some where between 0.1 and 0.01 which i'm sure you'll be pleased with.

But again don't too giddy because thats only resolution and it means nothing in accuracy terms if the machine bends like banana.!!

Now you'll want to know the speed you can expect.? So lets work on 900rpm which is realistic figure for stepper using R&P provided run on enough volts. (60-70v)

20.95mm x 900rpm = 18855mm/min or 18.85mtr/min which is just about spot on for decent sized plasma machine.! . . . . Well Done . .Lol

Edit: Opp's I forgot the ratio.!!
So it's 20.95 x (900/3) = 6285mm/min or 6.3mtr/min which is still ok for cutting but on the slow side for rapids on large machine.
In practise provided all is setup well and correct voltages etc I'd estimate 8mtr/min or more will be quite do-able.

warwick
28-11-2016, 03:25 PM
HELP!!!!!!
im just coming to the stage to order my pulleys for reduction on the x and y axis.......dean kindly worked out the 3-1 reduction with mod1 rack and pinion.........
iv actualy used mod1.5 with a 24t pinion spur gear..............if i order t5 60 tooth and 15 tooth will this be ok to get me back near the mod1 calculation in the above post???

JAZZCNC
28-11-2016, 04:26 PM
It's easy to work out if you know the Dp (Diametric pitch) of the pinion which for 24T Mod1.5 is 36mm. Then times this by pi to give the Linear pitch before ratio which in this case is 113mm.

Now you can work out ratio you'll need to give the desired linear Pitch. 15t/60t will give 4:1 ratio so 113 / 4 = 28.25mm. For Plasma this would work ok.

Ps: Word of warning before ordering make sure 15t pulley will fit your motor shaft because there won't be lot of pulley left for grub screws etc after it's bored.

warwick
10-12-2016, 06:39 PM
hi, just a few questions. is 100mm deep enough for a water table? and is there a prefered spacing for the slats??

many thanks