New Build - CNC Plasma Table

All things related to the Centroid Acorn Plasma system.

Moderator: cnckeith

ShawnM
Posts: 1215
Joined: Fri May 24, 2019 8:34 am
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CNC11: No
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CNC Control System Serial Number: 7804734C6498-0401191832
Location: Clearwater, FL

Re: New Build - CNC Plasma Table

Post by ShawnM »

That’s funny, I used the plasma table to make some brackets for itself also. I also use it to make custom backplanes for my other router retrofits that I do.

I don’t use sheet cam but many here do and they can show you how to have sheet cam automatically slow down in the corners and for circles. There are “rules” or something like that for sheets cam where you can customize it to automatically add things to the g code.

Each time you cut a new material spend some time just cutting 4” lines until you get good clean cuts and modify the Profile Manager with those new settings.
Joey
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Re: New Build - CNC Plasma Table

Post by Joey »

Just saw this Hypertherm powermax1000 for sale on Jeff's "CNC Plasma Table Builders" Facebook page. Looks like a heck of a deal.



We can have a TeamViewer session to set up your Sheetcam correctly for slowing down in arcs and tight circles. I just went through this with AtomicAsian.
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landmark573
Posts: 53
Joined: Mon Jun 24, 2019 3:30 pm
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Re: New Build - CNC Plasma Table

Post by landmark573 »

Thanks Joey. I've been on a trip so I'm just getting back to the build. I don't use Facebook but will look for the post. Probably too late anyway.

I did more testing on 18ga steel. I tried turning off smoothing and found that it slowed down considerably on the curves without adjusting any feed rates in the posted file. I even upped the feed rate in the profile to 200ipm and turned off smoothing. The cut was a lot smoother and the curves ran around 30ipm. I don't fully understand what smoothing does but my mechanical design doesn't fall into the sweet spot because I'm using direct drive rack and pinion with .4 turns per inch.

I will contact you to do a TeamViewer session when I get everything setup to do it.
landmark573
Posts: 53
Joined: Mon Jun 24, 2019 3:30 pm
Acorn CNC Controller: Yes
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DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
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Re: New Build - CNC Plasma Table

Post by landmark573 »

I am looking to add gearboxes to my X and Y axis motors. Currently I am running rack and pinion direct drive with about .4 turns per inch of travel. So my resolution isn't too good at .0015". The motors are nema 23 (spec's in google photo album linked below). The rack and spur gear spec's are there too. I would like to just sandwich the gearbox between my existing motors and the spur gear running on the rack. The shaft on my motors are 1/4" with a flat. The spur gears have a 3/8" bore with a set screw. I think a 3:1 ratio would be ideal. I've looked all over ebay but haven't found any. Does anyone have a good source for gearboxes?

https://photos.app.goo.gl/kNqNsR1g1UCafaFBA
Joey
Posts: 102
Joined: Tue Aug 17, 2021 10:51 am
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Re: New Build - CNC Plasma Table

Post by Joey »

Here is some photos on the gearboxes I used with my lead shine motors. Also have some photos of parts cut without the gearboxes and then with the gearboxes. The reduced gearing sure does help.

https://photos.app.goo.gl/SvcHwZBsK2rjyoR6A
ShawnM
Posts: 1215
Joined: Fri May 24, 2019 8:34 am
Acorn CNC Controller: Yes
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MPU11 & GPIO4D -w/ 3rd Party Drives: No
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CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: 7804734C6498-0401191832
Location: Clearwater, FL

Re: New Build - CNC Plasma Table

Post by ShawnM »

I just did a google search for nema 23 gearboxes 3:1 and the first hit was an ebay ad out of California. Are you sure you are looking hard enough? The second hit was an Amazon listing. They are everywhere.
landmark573
Posts: 53
Joined: Mon Jun 24, 2019 3:30 pm
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CNC11: No
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Re: New Build - CNC Plasma Table

Post by landmark573 »

I do find all kinds of gearboxes But I still didn't find a 3:1 gearbox with a 1/4" input and 3/8" output on ebay or amazon. I did find some 5:1 gearboxes with an 8mm input and unspecified (14mm>) output. I might be able to bore out my spur gears to 14mm but don't know about shimming the input.

I'm still looking but sourcing parts has never been my strong suit.
ShawnM
Posts: 1215
Joined: Fri May 24, 2019 8:34 am
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: 7804734C6498-0401191832
Location: Clearwater, FL

Re: New Build - CNC Plasma Table

Post by ShawnM »

It's certainly more tricky with imperial measurements when everything out there is metric. It might be easier to buy new motor/gearbox combos and then new pinions with the correct tooth count. The sizes you are finding on Amazon are very common. The last two sets of motors I removed for retrofit/upgrades were 14mm shafts and an earlier one was even 19mm.

Question, how do you have pinion gears with a 3/8" bore on a stepper motor with a 1/4" D shaft? Did you measure correctly? Something is off here.
landmark573
Posts: 53
Joined: Mon Jun 24, 2019 3:30 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: none

Re: New Build - CNC Plasma Table

Post by landmark573 »

I was able to find 3/8" OD bushings that I drilled out to 1/4". The pinion gears have a set screw so I drilled a hole in the bushing. Then aligned everything and tightened the set screw on the flat of the shaft.

The HobbyCNC 4-axis drive I got doesn't support 4 wire motors which is all I've seen with stepper / gearbox combos. I may end scrapping the whole drive system and make better choices. I hate to do that because I feel like after 5 years I'm so close to having a table that will handle my limited needs.
ShawnM
Posts: 1215
Joined: Fri May 24, 2019 8:34 am
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: 7804734C6498-0401191832
Location: Clearwater, FL

Re: New Build - CNC Plasma Table

Post by ShawnM »

Things like this happen, people start buying parts before they have the whole picture. Stepper drives are very inexpensive. Personally I'd scrap that hobby-cnc driver board and use real stepper drives. I feel those "all-in-one" are a bad idea because if you have an issue with one tiny part on the board the whole board is trash. Sell it and move on.

As for your motors, that's also a bad idea making bushings like you did. It's just one more thing to fail or come loose and cause problems. Now you have twice as many fail points on the drive system. With plasma you're gonna have high acceleration and deceleration moves and I fear those bushings are gonna be nothing but trouble. Stepper motors and drives both are so inexpensive these days. Get steppers with larger shafts and metric. Match motors and gear boxes first. Pinions are easy to find as well.

Many people try to save money in the beginning, and there's nothing wrong with that, but it can cost you more in the long run. Take a step back and make a new plan and you'll be much happier in the long run.

We'll get you back up and running in 5 weeks (not years), sound good? :mrgreen:
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