Steep Creek Fab 4'x5' build

[J0nesy]

Wanted to share my build with the experts here and get some feedback and advice. Might take several posts to get up to current progress.

Started off with drawing the design up in Solidworks.

3d pic 1.JPG

When I started the project and design, I was working for a large international CNC machine tool company. So they tossed out obsolete, used, or damaged parts frequently. That is how I acquired the aluminum extrusion, linear guides, and cable energy chains. The linear guide length is what determined the overall stroke of my machine. 48"x66" should be large enough to do anything I really need.

Overall this has been a slow moving project. I've tinkered with it on and off over the years as life gets in the way, marriage, moving, new job, etc. But since I've been working from home, it has become one of my Covid projects to get it fired up.

Specs:
48 x 66 inch working area
Dual 300 oz-in nema 23 motors on the gantry (Y axis)
Single 300 oz-in nema 23 motor on carriage (X axis)
Single 156 oz-in nema 23 on the Z axis
CNC4Newbie Z axis assembly
Floating z axis with micro switch
4" deep water table
2"x1/8" flat stock used for curved slats
#35 chain drive on X and Y axis'
10 tooth sprockets
Price THC
Hypertherm 45xp

Mach 3
Sheetcam
Solidworks

Current state of the machine

20201117_190056.jpg

I've been able to make some cuts with the machine. Simple shapes haven't been an issue. But of course the first complex sign I was asked to do for a friend has been kicking my butt.

Known issues or work left to do:
Upgrade Y axis motors to 425 oz-in motors ???
Swap over to Belt or rack and pinion on X and Y ???
Trim some weight off Gantry
Add tensioner to X axis chain
Dial in motor tuning (was just reading up on the topic this morning)
Do test cuts to determine best cut feed rate for my materials
Do test cuts to determine best THC voltage for my materials
Can't get fine cut consumable to hold an arc

These are supposed to be 3/8" diameter holes

20201117_185838.jpg

Rough looking cuts

20201117_164053.jpg

[acourtjester]

2 things Hypertherm as already done a chart got cutting spects do a search here on the fine cut nozzle for info on those.
Here is a video showing setting up the Price THC, other info posted in your other post (viewtopic.php?f=147&t=31429)

[J0nesy]

2 things Hypertherm as already done a chart got cutting spects do a search here on the fine cut nozzle for info on those.
Here is a video showing setting up the Price THC, other info posted in your other post (viewtopic.php?f=147&t=31429)

Thanks for the Price setup vid. I was struggling to figure out the best method to dial that in for each material.

[acourtjester]

You can do this for each metal thickness you normally cut but with the thinner metal use a weight on top of the metal to be sure it is flat for the testing. And cut away from previous cuts so the metal does not warp up and give you a false clearance readings. It becomes quicker as you see it function each test.
have fun
Tom

[adbuch]

I use the settings from the Hypertherm chart for Low Speed FineCut Mild Steel. They work well for me.
David

Low Speed FineCut Mild Steel.jpg

[adbuch]

I've been able to make some cuts with the machine. Simple shapes haven't been an issue. But of course the first complex sign I was asked to do for a friend has been kicking my butt.

Your holes look oval shaped. I would suggest attaching a sharpie to your torch mount (instead of cutting) and letting your machine draw your holes and letters to see what they look like. This may help you separate any mechanical issues from plasma cutter issues. If your letters still look wavy and your holes out of round when the machine draws them, then you know you have one or more mechanical issues.
David

[adbuch]

Here is a pen holder that looks easy to make.
David

https://www.youtube.com/watch?v=zPDTyza ... e=youtu.be

Pen holder video.jpg

[J0nesy]

I upgraded both gantry (Y axis) motors from the 300 oz-in motors to some 425 oz-in motors. This does seem to help with the sluggish motion I'm seeing. Now that I've bumped up the acceleration I need to do some bracing on the table legs, and trim some weight off the gantry assembly.

Also was able to take a look at some of the parameters in a turn key system that a local business has, and might play with some of the settings in sheet cam and mach 3 based on what I seen there.

I'll for sure try putting a pen on the torch to try and narrow down the issue.

[acourtjester]

When tuning the axis motors I use a rule of thumb where velocity will be like 100 and acceleration is like 25, or a 4 to 1 ration. If the acceleration is to high the motor will stall when it tries to move.

[J0nesy]

After beating my head against the wall trying to get some accurate cuts out my machine, I finally stopped by a friends shop that has a plasma table. Learned a few tips and tricks from them, and went home to tweak my setup. I know this will be an unpopular opinion based on other threads I read on this forum, but trying to run the book speeds just wasn't working out for me. I'm not in a production environment so the difference between a part taking 2 minutes or 4 minutes to cut doesn't really matter. So I just slowed my table way down (100 ipm range) and played with the amps on the Hypertherm. I finally realized that it is adjustable for a reason and I didn't need to run it turned all the way up.

I'm getting much more consistent and accurate cuts now. I've only burned up one full sheet of 18g so far, but I have another almost full sheet to cut for friends and family for Christmas gifts this year.
Also getting much more comfortable with draftsight and using it to trace over and design new parts. I'm a ME by trade and use Solidworks daily and occasionally use Draftsight as needed. The mindset shift from having everything be toleranced and exact dimensions to tracing a piece of "artwork" that has no dimensions or constraints other than aesthetics is something I'm struggling with a bit.

All the designs below were hand traced

[adbuch]

Good for you!
David

[J0nesy]

So an update on the table. I've ran probably 5 full (4x10) sheets of 18g through it in the past 6 weeks or so. The chain just isn't cutting it for accuracy and cut quality. So I spent my $600 stimulus check wisely and bought the rack and pinion kits from Avidcnc. This has lead to a nearly complete redesign. Hoping the Avidcnc stuff shows up soon. I ordered it a couple weeks ago, and my couple of followup emails have been unanswered. Anyone had bad dealings with Avidcnc before?

[adbuch]

I have had great "dealings" with Avidcnc. Over the last several years I have purchased 2 complete tables from them - the Pro4848 and Pro2448 - plus I have ordered other parts and accessories from them. I would suggest phoning them to follow up on your order for lead time and ship date/tracking numbers. I would give them an A++++ for their service and quality of products.
David

[SRdesign]

I recently ordered my rack and pinion parts from them as well. They were a little late on shipping estimates but they responded to my email within the day I sent it. Did you send your email to: support@avidcnc.com ?
Their response was they were having a delay on timing pulley parts.

[J0nesy]

I finally got them on the phone. They were waiting for updated information on some backordered parts before they responded to me. One of the components is still 4-5 weeks out, so I'm going to upgrade to the Pro series for a discounted price so I can get parts sooner.