THC not responding < machine mechanicals need addressed>

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ShawnM
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Re: THC not responding

Post by ShawnM »

Don't change your anti-dive number, that will screw up all your other profiles. No one suggested you change that number nor should you.

Did you do a test cut to see what the target voltage is for that material? Just create a new profile for the 26 gauge material and edit those settings, not the anti-dive.

You have not recalculated the Z axis, do this first. Try lowering the Accel to .2 on the Z axis.

Please, please take the time to tune and setup the machine parameters before you keep cutting material. You keep posting problems with the machine but you wont take the time to set it up properly or take the advice of those who have been down the same road you are on.

I mentioned this to him Keith, there's no way it's exactly 4.00
Joey
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Re: THC not responding

Post by Joey »

So We did some investigating last night and checked out the Plots coming from Atomic's THC. Sorry I forgot Atomic's name again the username Atomic Asian just sticks in my head. When looking at the Plot the THC was not activating because the Motors would not come up to full feed rate unless it was an extremely long straight cut which happened to be on the X axis. Seeing the feed rate take forever to come up to speed hinted at a possible custom smoothing setting being applied. Sure enough the custom smoothing setting being applied wasn't the best, so we went back to the default "precision" smoothing preset. Now the Job was able to attain full feed rate a lot quicker allowing for more THC time in the job. But to my Surprise THC was still not enabling, turns out even when the motors were able to get up to speed they would reach full speed then mediately step back to about 89% of the target feed rate. This caused THC velocity anti dive to never actually allow THC to enable. Velocity anti dive ratio, Means THC will enable when the XY velocity reaches at least 90% of the Target feed rate.

The THC Plot is awesome to work with in these situations. Being able to see the cause and affect with THC, Voltage and XY Velocity saves so much time and guess work. We then set the THC velocity anti dive ratio from the 90% default down to 85%, putting a band aid on the issue. The issue with the Feed rate is due to the motor/drives tunning and the tables Gantry. Atomic is working on a dual motor Gantry which is the industry standard. Without a dual motor gantry, problems occur with speed and stability.

I returned the Anti Dive threshold back from 60% to the default 7%. Then quickly found out that the Z feedrate was not quick enough to keep up with the material surface when the THC would quickly see voltages higher than 7 percent of the Target voltage thus enacting anti-dive. So the Anti dive number had to be adjusted up until we arrived at about 55%. The lack of speed in the Z axis is due to the Z not having the proper settings in the wizard. I think Shawn is helping Atomic to better tune his z axis and help apply the correct setting for faster Z moves. Atomics new Gantry will likely solve his table's Z capabilities. Tho figuring out how much he can push the Z speed will also help with his current set up.

The THC config menu is not meant to be changed like you see here. This is just asking for trouble and with a Anti Dive threshold like 55% the Z will crash into the table/material because of big voltage changes. Atomic's table is a work in progress, and he is rebuilding the gantry and still making adjustment/improvements to his machine. The Goal was to get Atomic cutting with what he had at that moment. With our Default THC Config setting there is no need for THC ON/OFF codes in the G-Code since any slow down or spike in voltage will turn off THC. But in a case Like Atomic's THC Config settings, it is now a must to have THC ON/OFF codes at any corners or slowdowns. Atomic and I were getting away with no THC ON/OFF codes last night with the job/material but it is only a matter of time before THC reacts badly and raises way to high or crashes. I think the only thing that saves his torch from crashing is the fact that the z doesn't move quick enough to react to spike and drops in voltage. The Z is always playing catchup to what the voltage is doing allowing for a smooth ride. :lol:

Note: A good way to narrow down and find the limits of the accel/decel of an axis is to just run a repeated movement. So start off at a .4 accel/decel rate and run the job on repeat to see if any steps are lost and that the axis can handle this rate. Then up the speed once the axis is known to be able to handle the accel/decel rate. A good increment of increase or decrease is about 20%. Once the Axis reaches an accel/decel rate that it cannot handle and loses steps just back off 20% there is the new accel/decel of the axis.
Last edited by Joey on Thu Sep 22, 2022 5:33 pm, edited 1 time in total.
AtomicAsian
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Re: THC not responding

Post by AtomicAsian »

once again Joey has saved the day.
I owe him big time.
I did configure the Z axis this morning.
3.878785455. much better.
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ShawnM
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Re: THC not responding

Post by ShawnM »

Awesome news and progress is being made for sure. Try changing the accel/decel on the Z axis to .2 and see if it can keep up. As I said before a "snappy" Z is important. Is RAS off on the Z axis?
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Re: THC not responding < machine mechanicals need addressed>

Post by jcoldon »

First I'm Gona respond about this kikoi table build. i helped do few retro on them 1 thing i see them clear path motor to small for that table the retro used a 750 watt servo AC . that table lacks due to only 1 motor on Y axis and high speed it shakes . Kiokie designed that setup for sheet metal duct cutting . using plasma table that lacks high acceleration and speed using Hypertherm plasma never get good cuts you have to fudge lot settings . Acorn profile mgr built in settings are designed for book speeds . Wana know more about that table how to improve it Go on Face book page CNC plasma table builders . contact Jessy brown he dun a lot of upgrades to that table could give you better impute on things he dun to make it better
jcoldon
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Re: THC not responding < machine mechanicals need addressed>

Post by jcoldon »

I just saw a pic of your Y axis motor looks like you have a large 2 inch pinion gear on a 5 to 1 planetary that gone loose acceleration that setup you need 10 to 1 i always recommend 10 to 1 on servo and high rpm servo if that power is needed . that table used a plate rider to cut height was constant never moved
AtomicAsian
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Re: THC not responding < machine mechanicals need addressed>

Post by AtomicAsian »

I’ll change it tomorrow. yes the RAS is disabled
AtomicAsian
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Re: THC not responding < machine mechanicals need addressed>

Post by AtomicAsian »

jcoldon wrote: Thu Sep 22, 2022 6:47 pm I just saw a pic of your Y axis motor looks like you have a large 2 inch pinion gear on a 5 to 1 planetary that gone loose acceleration that setup you need 10 to 1 i always recommend 10 to 1 on servo and high rpm servo if that power is needed . that table used a plate rider to cut height was constant never moved
yes i did have the 2in pinion on a 10:1 gearbox. i recently changed to a 5:1 and a smaller 24tooth pinion.
cnckeith
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Re: THC not responding < machine mechanicals need addressed>

Post by cnckeith »

always test machine movement before cutting so you know and are familiar with its operating parameters and adjust mechanicals to put the machine in the plasma sweet spot as outlined in the Plasma Manual.

with steps per rev on drive set to 1600 or higher

and overall turns ratio of 1 or higher but not to exceed 2.5.....

Test and verify machine motion (without cutting) write a g code program or use MDI

G0x48y48
G0x0y0

observe and adjust

- accell/decell

- max rate (increase until fail, then back off 20%)

then do same for Z axis.

for good motion. once max rate is determined then you know that if you ask the machine to move faster than that in the profile manager it wont be able to do it. etc.

if good motion can not be achieved mechanical adjustments will be necessary. such as but not limited to. Axis motor type and size change, overall turns ratio change so the motor used has the power and speed needed to move that axis in the Plasma Sweet spot.

is this gantry being driven from one side? or are there two axis motors for this axis (one on each side)?
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