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voltage settings way too low.

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cruz
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voltage settings way too low.

Postby cruz » Tue Jul 03, 2018 10:45 am

hello,

next issue with my table setup :roll:

the voltage settings i need to use with my Compact THC Controller 150 for the right(isch) cut height is WAY lower than what hyperthem says.
i'm using a hypertherm105 with a watertable and a floating head.


15mm steel 85A
109 volt for manually setting
133 volt for hypertherm setting


finecut 3mm steel
58 volt for manually setting
78 volt for hypertherm setting

with the THC set manually the quality is about 90% of what it should/could be.
the way i get to my settings was told to me by the table vendor after i called him about it:
- zero the z-axis manually and set it to the correct cut height.
- turn THC off
- cut a straight line of 100mm, the voltage you read at the THC is the voltage that should be used when cutting with THC on.

i know that somewhere Jim Colt said that cut height is more important then the voltage.
but my setting are so far off, that i'm thinking something is wrong.
mabye with the THC?

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acourtjester
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Re: voltage settings way too low.

Postby acourtjester » Tue Jul 03, 2018 11:37 am

Well I have used a few different THC units, Proma has been one, I have observed that same effect. As Jim states cut height is the most important of the setup. There are things the effect arc voltage and that is why a stating procedure of finding what you table voltage is without the THC on at the correct torch height. I have had Promas the worked only using Raw Voltage and others with the 50:1 divider. I have had a Longevity Plasma with a Proma and it seemed that almost all metal cut around 100 arc voltage. I had another table using a DTHC-IV and it followed the Hypertherm manual on the money.
Just go through the setup for each metal thickness and speed and develop a chart that will work with your table and use it. Again setup the correct cut height and then find the arc voltage for each.
Be sure you have the cut height at 0.060" where it is actually cutting after about 4" to 5" of travel to be sure the floating head switch is set correctly. you can do this without the plasma on.
this may help
https://www.youtube.com/watch?v=6CDml_kosbY
this shows with a ohmic sensor
https://www.youtube.com/watch?v=irhDCCx9JCg
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
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Drag Knife and Scribe
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13" metal lathe
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Everlast PM 256 tig

cruz
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Re: voltage settings way too low.

Postby cruz » Tue Jul 03, 2018 5:08 pm

hey acourtjester,

thanks for the info,
how would i know if my proma works with raw voltage or with the 50:1 divider?

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acourtjester
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Re: voltage settings way too low.

Postby acourtjester » Tue Jul 03, 2018 5:34 pm

Well if you hook it up the the CPC connector on the back of your plasma unit that is the 50:1 output ( or the divider output it can be other ratios like as there are about 5 different ratios). Or it can be hooked up to the front panel wire connections from the work lead and torch cable.
This would be the raw voltage output if you check it with a meter you will see the actual arc voltage (like 80 to 130 volts DC) only do this if you know how and what you are doing, you will not be happy if you mess up.
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PM 256 tig

cruz
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Joined: Wed Apr 18, 2018 2:14 pm

Re: voltage settings way too low.

Postby cruz » Wed Jul 04, 2018 1:03 pm

acourtjester wrote:Well if you hook it up the the CPC connector on the back of your plasma unit that is the 50:1 output ( or the divider output it can be other ratios like as there are about 5 different ratios). Or it can be hooked up to the front panel wire connections from the work lead and torch cable.
This would be the raw voltage output if you check it with a meter you will see the actual arc voltage (like 80 to 130 volts DC) only do this if you know how and what you are doing, you will not be happy if you mess up.

there are no wires connected to the lead and torch on the front, so it must be the 50:1 output.
could the problem be there?
something with the deviding not being correct?

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acourtjester
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Re: voltage settings way too low.

Postby acourtjester » Wed Jul 04, 2018 4:44 pm

I cannot tell you if the Hypertherm 105 has a voltage divider built in or not but if your getting voltage signal out to the Proma it may have one.
That points back to the Proma not working well with the lower voltage signals, as stated above with the promas I have used some seem to work better with the "Raw Voltage" signals. In their manual they show how to hook the proma up both way.
One thing to check is the connection for the signal Comm is not the same as the power negative and should not be connected together. The signals output (arc ok,up, and down and Comm) are connected to the BOB board and the power in is separate.
DIY 4X4 Plasma/Router Table
CandCNC DTHC-IV & Feather Touch
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PM 256 tig

jimcolt
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Re: voltage settings way too low.

Postby jimcolt » Sun Jul 08, 2018 10:26 am

If you are running at book speeds and at the book cut height (usually .06") with new consumables and at the book amperage settings....then I 100% guarantee that the Hypertherm arc voltages listed in the cut charts are correct. They were all developed in an advanced engineering lab using calibrated equipment. The problem is that almost anything you change when plasma cutting will affect the voltage / physical cut height relationship, and further, many of the low cost THC's are not accurately calibrated, and have no means to be re-calibrated (my experience with them!). Here are the things that affect cut voltage and cut height:
- Cut speed. slower means the arc gets longer and the voltage is higher....so the THC moves torch closer to material. Faster speeds (than book) will raise the torch.
- Air pressure, purity. The arc is a resistor in an electrical circuit. Change the pressure of the air or the purity of the air and the resistance changes, which will change the voltage / height relationship.
- Consumable wear. As the electrode wears and develops a pit on the hafnium insert...the torch will move closer to the material. On THC's that have an voltage sampling this is automatically compensated for. On machines that require either the CAM software or the operator to set an arc voltage setting....you must increase voltage by as much as 10 to 15 volts as the electrode wears in order to maintain the correct cut height.
- Acceleration. Regardless of the cut speed you set...all machines will slowdown when entering corners or on holes. The amount that they slow down is dependent on the design of the machine. Small motors, incorrect gear reduction, heavy mass to move and incorrect drive tuning will cause sluggish acceleration and diving in corners and on intricate details. Better height controls are tightly integrated with the cnc and freeze height when cut speed slows, eliminating diving. Many low cost THC's dive the torch in intricate detail during deceleration.

So, if your machine has calibration issues and it seems to always require 20 volts more that the Hypertherm cut charts say.....well just run every cut with a 20 volt higher setting.....I find that that often works. If you have a particular part that you like to cut at 1/2 the book speed...., then find the voltage that works to maintain the cut height listed in the charts...and use that.

If you are curious about the real arc voltage when you are cutting at a particular voltage.....get a voltameter, set it on a 300 volt cale and commect it to the raw arc voltage terminals inside the power supply. Essentially the negative lead of the meter is connected to the torch electrode connection and the positive to the work clamp. This will show the actual arc voltage while cutting. If the voltmeter reads 130 volts and your THC readout reads 100 volts.....then expect that your THC electronics are out of calibration by 30 volts. Jim Colt Hypertherm

cruz
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Re: voltage settings way too low.

Postby cruz » Sun Jul 08, 2018 10:38 am

hey Jim,

thanks for the clarification, since i don't have that special voltameter and it seems to be a case of following the specs from hypertherm as close a possible to then use the volts that are required for the correct cut height.
i'm gonna leave it at that.

btw just a random question with the powermax105 would it be possible cutting 30mm (1.18")?
the hypertherm book says it can cut 32mm (edge start) but would the quality be good then (edge angle)?

tcaudle
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Re: voltage settings way too low.

Postby tcaudle » Sun Jul 08, 2018 4:56 pm

Virtually any DVM you can buy will measure that high and down into the millivolts range too. Even the cheap ones are usually auto scaling. Having a DVM in the shop tha can measure DC volts and AC volts and resistance (ohms) is a really handy tool. You don't need a high dollar Fluke meter. Most are plenty accurate costs less than 35 bucks and have enough scaling to do what you need around the shop.

john527
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Re: voltage settings way too low.

Postby john527 » Mon Jul 30, 2018 5:36 am

I am some what new to plasma cutting, just got my new plasmacam and new Hypertherm 45XP about 4 months ago, and all I can say so far is everything I have cut so far using hypertherm book specs have cut perfect! Keep your consumables in good shape and life is good!


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