DIY cnc Plasma finally underway
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DIY cnc Plasma finally underway
The start of my plasma table it will have a little over 4 x 2 cutting area, myplasm components aside it will be a cheap no frills build.
still waiting on several bits one being a much shorter ball screw for the x and i need to chop down the rail on it also.
still waiting on several bits one being a much shorter ball screw for the x and i need to chop down the rail on it also.
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Re: DIY cnc Plasma finally underway
Water table ? If so: Don't make the mistake I made. I made an angle picture frame with sheet welded in the center(edges of the angle..albeit my table is larger) to make the table. Get a piece bent up on a brake and weld the corners up. Use stainless.
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Re: DIY cnc Plasma finally underway
Thanks tjs my bodged attempt at the water table is here ive got to bully it into shape as well as patch it up but it should be ok.
- acourtjester
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Re: DIY cnc Plasma finally underway
Good show many DIY types here (Me too built a few tables from scratch), you will be very happy when you finish things up. Feel free to ask questions about things to help you along. Go ahead and assemble the parts you have to see if they need to be changed or not. That way you making progress and you will be able to change or upgrade later. You said you have had other CNC projects so you have the big picture and understand the software end too.
DIY 4X4 Plasma/Router Table
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
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Re: DIY cnc Plasma finally underway
Thanks pal
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Re: DIY cnc Plasma finally underway
Using ballscrews for linear motion for a plasma table typically does not end weell
There are two reasons:
1. Linear speed is the motor RPM (typically around 800 RPM max be for it stalls under load) DIVIDED by the TPI of the lead screw. If you use a typical one of say 5 TPI you get 160 IPM. Means you have to cut thinner material at feedrates a lot lower than called for and deal with the increased kerf width, increase slag and diving torch. Numbers get worse if the TPI is higher.
2. Seems like a simple solution is to gear the interface between motor and ballscrew up to spin it faster BUT there is a physical limitiation call "lead whip" that occurs. The faster you spin a long screw the more it bends the screw form centrifugal forces. The smaller the screw the sooner it happens.. It will be obvious when it does because your table will vibrate and it can get violent.
One of the reasons you see most plasma tables built with rack and pinion or belt drive is because the ratios work the other way
Ballscrews are GREAT for routers and milling machines where accuracy is more important than speed. Since the myplasma supports neither you have some issues to address.
An ultra light gantry and a direst drive pinion to rack (smallest diameter pinion you can use ) will give you the speeds you need . Of course driving both ends of the gantry is best to prevent racking
There are two reasons:
1. Linear speed is the motor RPM (typically around 800 RPM max be for it stalls under load) DIVIDED by the TPI of the lead screw. If you use a typical one of say 5 TPI you get 160 IPM. Means you have to cut thinner material at feedrates a lot lower than called for and deal with the increased kerf width, increase slag and diving torch. Numbers get worse if the TPI is higher.
2. Seems like a simple solution is to gear the interface between motor and ballscrew up to spin it faster BUT there is a physical limitiation call "lead whip" that occurs. The faster you spin a long screw the more it bends the screw form centrifugal forces. The smaller the screw the sooner it happens.. It will be obvious when it does because your table will vibrate and it can get violent.
One of the reasons you see most plasma tables built with rack and pinion or belt drive is because the ratios work the other way
Ballscrews are GREAT for routers and milling machines where accuracy is more important than speed. Since the myplasma supports neither you have some issues to address.
An ultra light gantry and a direst drive pinion to rack (smallest diameter pinion you can use ) will give you the speeds you need . Of course driving both ends of the gantry is best to prevent racking
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Re: DIY cnc Plasma finally underway
Thanks' for the great advice folks
I see people out there running screws on the smaller machines and think i would be happy with those cuts but they don't show the limitations you pointed out so i might as well eliminate those while I'm at this stage.
I've now sourced rack and pinion.but i did originally want to stick to the solo X axis beam(60mm extrusion) but i fear now with it going to have rack mounted and the stepper moving along it as opposed to being fixed at the back end it might create issues, so i have to chew on whether to do away with that and go for a rail plus RnP either side.
Im also going to replace the tb6600 drivers i bought with DM556T
Thanks again darren
- acourtjester
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Re: DIY cnc Plasma finally underway
You do not need to have 2 motors to drive an axis, all the table I have built use a cross shaft to drive the axis on both sides with one motor. the cross shaft passes through the rail to drive both sides, works great. I have never had the out of square tables with dual motors sometime have.
![Funny :HaHa](./images/smilies/icon_new_haha.gif)
![Funny :HaHa](./images/smilies/icon_new_haha.gif)
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DIY 4X4 Plasma/Router Table
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
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Re: DIY cnc Plasma finally underway
Nice idea,I haven't come across that one before. ![Wink :wink:](./images/smilies/icon_e_wink.gif)
![Wink :wink:](./images/smilies/icon_e_wink.gif)
- SegoMan DeSigns
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Re: DIY cnc Plasma finally underway
Sprocket heads Rule!
I had to do mine different than Tom's due to the weight of my gantry (400 lbs). I did not want to much side load on the motors so the X axis has its own chains with tensioners that the gantry bolts to, then the jack shaft that feeds the chains has a spring loaded ant-back lash and gear reduction,
The SxS was added to assist in acceleration and drifting around corners.
I had to do mine different than Tom's due to the weight of my gantry (400 lbs). I did not want to much side load on the motors so the X axis has its own chains with tensioners that the gantry bolts to, then the jack shaft that feeds the chains has a spring loaded ant-back lash and gear reduction,
The SxS was added to assist in acceleration and drifting around corners.
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- djreiswig
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Re: DIY cnc Plasma finally underway
It's the little details that make all the difference.SegoMan DeSigns wrote: ↑Mon Oct 02, 2023 1:05 pm The SxS was added to assist in acceleration and drifting around corners.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
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C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
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Re: DIY cnc Plasma finally underway
Great looking build, be sure to post some pics when you have it completed!
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