Cutmaster 52 beveled edges

[TerraWombat]

First, I will say that one of my biggest regrets when I purchased my CNC plasma setup was not getting a Hypertherm unit. I love the amount of support that Jim Colt provides across multiple CNC forums. I'm not even sure how he's able to keep up with all of the questions on each.

Anyway, I'm looking into the possibility of starting to use my 4x4 CNC plasma machine to turn a profit. Most of the cuts I will be making will be in 3/16" and 1/4" steel making random automotive brackets. Last night, I cut a set of prototypes out and was disappointed with the amount of bevel on the edges. Although it doesn't matter too much to me, this isn't the type of quality I would ever provide to any of my potential customers. I understand that no matter what I do, the plasma cutting process will produce about a 5 degree bevel, however, I'm in the 10-15 degree range. Definitely noticeable and it greatly effects the sizing of any holes.

I've read multiple posts by Jim that lay out some guidelines on reducing bevel, unfortunately, it's always crafted for Hypertherm machines. I went the Thermal Dynamics route to save a little bit of cash, but I'm thinking I may be paying for it in the long run. So far, here is what I have done:

Checked for torch squareness to the workpiece. The setup of my z-axis is awkward and it doesn't allow for any of the machinist's squares I own to fit in the tight space to check torch squareness. If I raise the torch off the workpiece about 3 inches, I can squeeze it in and do a very rough check. I have done this and gotten the torch as square as I can. I did order some smaller (1.5" and 2") machinist's squares that should be in next week. I'm hoping these will be of more use than the 6" one that I have now.

Checked the condition of the tip. I'm currently using a 40A tip to cut 1/4" steel plate. My plasma machine is set to 40A as well. The condition of the original tip wasn't great so I threw a brand new one on before I made the cuts in the 1/4". I inspected the electrode and was black near the tip, but it didn't seem to be physically damaged so I left it.

Checked the feedrate and tip height settings. I use sheetcam for post-processing and I've made several tool profiles for each thickness/material. For 1/4" steel, my feedrate is 36 IPM. My pierce height is 0.2" and my cut height is 0.19". These are all per the manual, except for the feedrate. The feedrate differs depending on if I have a shielded tip (25PM) or an exposed tip (40IPM). I think I'm getting confused on what exactly I have. My tip sure seems "exposed." I can see it with my eyes, but I do have a shielded cap deflector installed on the deflector cap as that's the way my machine torch was shipped to me, so I left it on. Perhaps I'm getting caught up in the lingo and am not following the manufacturers recommendations? Could someone clue in an idiot as to what the heck I have? Here is a list of parts I have installed in my torch, by part number:

SL100 Machine torch
9-8215 Electrode
9-8213 Start Cartridge
9-8207 Drag Tip 40A Tip (should I be using the 9-8208 40A tip with the machine torch?)
9-8237 Shield Cup
9-8243 Shield Cap Deflector

To better illustrate this I have attached a picture.

From reading Jim's posts about the Hypertherm machines, it seems like the spec for the standoff height in the TD manual is pretty high. I do have a torch height control installed on my machine, but I've never really though to look at the LED readout to see what the volts are at, but I recall them being in the 100-110 range. I believe that my THC is working as I have seen the Z axis DRO in Mach 3 change slightly as it move around the plate. 100-110 seems to be in the ballpark for a TD with an exposed tip, but a little low for shielded. Again, I don't think I really know what I have!

Sorry to make this into such a novel, but I'm trying to get as much info out there as possible. Any other TD owners care to share what they use for cut height and feedrate on 1/4" steel? Thanks!

[plasmanewbie]

I use a 9-8208 tip for 40 amp cutting...not sure what the difference is.

I have found that when I used to have problems with heavy bevel on my edge it was because my air supply had too much moisture. After I got that cleared up everything started to work so much better.

I read here that if you have black burning marks swirling around your electrode and inside your tip that you have bad air. My consumables burn clean now things are working great.

I cut 1/4 at 40 amps around 40ipm with a cutting height of .100 and get really good results. Best of luck

[TerraWombat]

Thanks for your response! In the midst of writing my multi-chapter novel, I completely forgot to mention my air supply.

It stinks. I have a 240V, 60-gallon, two-piston compressor that pumps out more than enough CFM to keep up with the plasma cutter and is filtered using a Frantz air filter with a roll of toilet paper (don't laugh...it works!), but my pressure shutoff switch went bad and no longer turned the motor off. So, I switched to my Home Depot-brand 30-gallon tank with oil-less compressor with no air filtration system on it, other than the built-in one on my TD plasma machine. So, there is potential problem number one.

I see that you're running at roughly half of the recommended standoff height. Can I ask why? Or is it nothing more than experience and tweaking the settings to get the optimal cut?

I'm also curious as to the difference between the 9-8208 and 9-8207 tips. I'll have to pose that question to the manufacturer.

Thanks again!

[srp]

The tip you want to be using is the machine tip. The resulting cut is much better than the drag tip. If you have black showing up I would suspect moisture. there can't be enough said about the importance of dry air. I would suggest a refrigerated air drier. Your Home Depot brand air compressor most likely will not keep up with air requirement of your machine and you might be running on less than optimal air pressure. Your cutting height at .19 is good. I would not cut closer. Just verify that is is actually at that height. Your machine and torch will achieve the excellent results you are looking for. These problems are only bumps in the road. Be sure to post what your results are. - John

[jmsrbrt]

I'll add that I do not have a refrigerated dryer, but rather my air leaves the compressor and travels through 50 feet of air line, then through a desicant dryer from Harbor Freight, then through my TD Cutmaster 51 (or 52, I forget). The aire is dry and believe it or not, and feels a little cool blowing across my hand. Bob.

[TerraWombat]

I'll add that I do not have a refrigerated dryer, but rather my air leaves the compressor and travels through 50 feet of air line, then through a desicant dryer from Harbor Freight, then through my TD Cutmaster 51 (or 52, I forget). The aire is dry and believe it or not, and feels a little cool blowing across my hand. Bob.

I'm actually about 10 minutes from heading out the door to my Harbor freight to pick up their dessicant dryer. I dug up a bunch of old threads on various forums where people have talked of a lot of success using this dryer as long as you keep the media changed often. You can also bake it in an oven to get the moisture out, too, but it would probably just be cheaper to buy another bag.

A refrigerated dryer would be ideal, but I don't know if I can swing that at the moment, unless I can find a good, used one. I see some really nice ones pop up on Craigslist all the time so I'll keep an eye out.

Thanks for the tips, everyone. I'll be sure to update this thread with my results.

[TerraWombat]

I just got back from HF and was pleasantly surprised when their dessicant dryer rang up at $19.99 and the two boxes of silica that I got rang up at $2.77 each. I'll look into getting this installed sometime early next week and will post results.

[jimcolt]

I would suggest using the 40 amp tip listed in the chart you posted, but not with the drag shield, use the exposed parts. .190" is very high to be running off the plate....and too much height causes more bevel. The T-D torches do generally operate at higher standoffs as compared to the Hypertherm torches, however I think you should be down around .08 to .10".....dial the arc voltage down (lower number) during a cut, and watch the torch as it gets closer to the plate....08" is about the thickness of a nickel. I think you will see an improvement in bevel with closer height.

Jim Colt

[TerraWombat]

Thanks for the response, Jim. I was thinking that the cut height seemed a little too much, but wanted to wait until someone else chimed in before I futzed with it. The first step is going to be to fix my main compressor and get the dessicant dyer setup on it for a source of cleaner, dryer air. If that doesn't produce the results I'm looking for I may start looking into the torch standoff. I'll also do a "dry" run and measure the static height to make sure that is working properly.

Also, can anyone comment on if my tip setup is "exposed" or "shielded"? There are two different cut charts in the TD manual for each setup and the specs are drastically different so I just want to be sure I'm looking at the right ones.

Thanks again, fellas!

[jmsrbrt]

I have the Cutmaster 51 (or 52, I forget) and use the 8208 tip, 8237 body and 8243 deflector on my machine torch. The 8218 cup and 8251 guide are on my HAND torch.

[TerraWombat]

I stuck with the original torch setup in my original post to kind of do a before and after comparison. I also spoke with a TD customer service rep and he directed me to the cutting charts of their automated plasma system, the A60. He mentioned that this system shares a lot of the same internal components as my CutMaster 52 and that the machine torches are identical and use identical internal components. The differences between the A60 cutting charts and the CM52 cutting charts weren't drastic, but it did lower the cut height some, which is one of the things I thought was a bit out of whack to begin with and the cutting speed was slightly faster.

So, with a desiccant dryer and some new settings, I cut out some pieces in 1/4" plate. It seems as though the edge bevel on any exterior cut has improved a lot, however, I've noticed that interior cuts (i.e. round holes in a bracket) still have a nice bevel to them. I can post some pictures up later to better illustrate this. In the meantime, anyone have any tips or ideas?

Thanks!

[jmsrbrt]

On the holes, maybe slow your speed down a little?