Are JD2 and shop sabre type gantry overkill for plasma?

[robertspark]

Just go with one of these VVVV



I've used this a few times in different posts, and in my opinion (like rear ends = everyones got one:) )....

its a bit oversized..... but I'm sure it works great and runs fast and does everything and churns out 1000's of tonnes of steel a day, week or whatever. But it probably could have been designed a little different and it would have lowered the weight that is being flung around at 600in/min and >0.3G.

If it's got a drill head attachement or a router or a mill head or mag-drill then sure it makes sense, but with just a plasma machine torch, I think (opinion) it's a bit over sized.

(would love to know a bit more about it from the builder if they ever drop in)

[SegoMan DeSigns]

I am drawing a blank on your image

[mikeysp]

I know we you have answered my question, but I thought this extract from an older thread added emphasis to the discussion: Jim Colt Quote BOLDED for my emphasis): "It is interesting to me with the hundreds of DIY machine builds.....how many builders are more concerned with "heavy duty" construction, and not with proper motor sizing, acceleration, etc. When I see a good lightweight machine design that is rigid, light, and the builder obviously did the homework regarding acceleration and following error.....then I know my plasma torches will provide good cut quality throughout the entire speed range. Lightweight is good! Jim Colt Hypertherm"

-Mike

[adbuch]

I know we you have answered my question, but I thought this extract from an older thread added emphasis to the discussion: Jim Colt Quote BOLDED for my emphasis): "It is interesting to me with the hundreds of DIY machine builds.....how many builders are more concerned with "heavy duty" construction, and not with proper motor sizing, acceleration, etc. When I see a good lightweight machine design that is rigid, light, and the builder obviously did the homework regarding acceleration and following error.....then I know my plasma torches will provide good cut quality throughout the entire speed range. Lightweight is good! Jim Colt Hypertherm"

-Mike

[robertspark]

.

in my opinion..... (everyone has one and they all will be different).... lightweight and therefore fast is better.

as I said^^^

[adbuch]

.

in my opinion..... (everyone has one and they all will be different).... lightweight and therefore fast is better.

as I said^^^

[SegoMan DeSigns]

(would love to know a bit more about it from the builder if they ever drop in)

Here is a vid on it:



And the build:

https://www.cnczone.com/forums/plasma-e ... tware.html

[mikeysp]

So, can I have an "opinion" of which high quality rigid lightweight gantry table on the market you would emulate if you were building. I am definitely not building that big red monster as I am only using my table for plasma and scribing. I plan to use a welded heavy-duty table with water bladder, and I really like the examples where the table side rails are below pan height. However, I care not for that right now. I am wondering what material type + dimensions are very rigid and light weight for a 5x10 table. I like the simple light design of the plasma cams, but I will be scribing too, and at this point I would be in uneducated opinion mode and likely overbuild or under build which is to be avoided.

Thanks. -Mike

[SegoMan DeSigns]

Mike,

Have you determined what type of rails and how you are going to move it yet? Those factors will determine what size of material is needed for mounting.

Here is a link to the 80/20 profiles:

https://8020.net/

It is really handy stuff to work with however the prices can add up quickly, I was looking at some of their 3"x6" profile but by the time I paid for all of the nuts, over length / weight shipping fees I was in the $800+ range so I went with a 4x6x1/8 rect steel tubing and got 20' for $150. The strange part of the equation is it was the same weight / ft but I had to drill and tap a lot of holes, I have a bunch of drill press's & a tapping machine so it was not a problem on this end.

Go by your steel suppliers yard and ask for a metal book showing metal profiles for your reference and designing needs.

Without knowing any of your design I would guestimate something in the 3x4x1/8 wall range would work for you if you choose steel over the AL profiles,

Steve

[robertspark]

(would love to know a bit more about it from the builder if they ever drop in)

Here is a vid on it:



And the build:

https://www.cnczone.com/forums/plasma-e ... tware.html

thanks I'll check it out, I always wondered why so big a gantry (appreciate the orientation but still seems very big for a plasma

[adbuch]

So, can I have an "opinion" of which high quality rigid lightweight gantry table on the market you would emulate if you were building. I am definitely not building that big red monster as I am only using my table for plasma and scribing. I plan to use a welded heavy-duty table with water bladder, and I really like the examples where the table side rails are below pan height. However, I care not for that right now. I am wondering what material type + dimensions are very rigid and light weight for a 5x10 table. I like the simple light design of the plasma cams, but I will be scribing too, and at this point I would be in uneducated opinion mode and likely overbuild or under build which is to be avoided.

Thanks. -Mike

I use one of my Plasmacam tables for scribing/engraving, and they can also be used for wood routing. Plasmacam rates the table for the DHC2 with the load capacity to support a full 1" thick steel sheet, although I have seen an example where they showed one of their tables stacked up with many more sheets just to illustrate their built in safety factor for table loading. If you want to do larger sheets, then take a look at the frame structure for the Plasmacam Sampson 510 5 x 10 table. I'm pretty sure the legs, frame, and gantry are constructed from the equivalent wall thickness material as their DHC2 4 x 4. You could give Plasmacam a call to find out for sure.
David

https://samsoncnc.com/

sampson 510.jpg

[mikeysp]

Ok, interesting that the 4x6 1/8" wall steel was no heavier than the aluminum 3x6. I will probably use steel. I will see if I can find out the samson gantry wall thickness. That machine screams at a 1000 IPM cutting speed capability. Would love to bump into one of those for a song. About 3 years ago I saw a 4x4 Plasma cam table from a high school that never used it for $750. My Dodge Diesel had caught fire 3 days earlier and I just didn't have my head on straight and I decided not to get it. Kicking myself since.

What do you think about ease of loading/unloading of a plasmacam vs. the tables with the rails down below the tabletop height? I had in my mind to extend the rails past the end of the table also, so I can have gantry well out of the way for loading/unloading steel.

I have a bunch of 3"x3" 3/16" wall for legs of table, so I am hoping to incorporate it.

Once I have a fairly lightweight solution, I will see what electronics are needed to move it. I have the idea of steppers with a 3:1 reduction for detail and rack and pinion. This is based on my thinking a few years ago though. I have never looked at servo electronics because it was out of my budget before. I am not sure what the fastest cutting speed I would use, so I hope to match the electronics to be able to do so. I cannot imagine 1000 IPM like that Sampson, but I am ignorant at this point. It would seem that I will not need servos to have fast cutting speeds; but I have noted that the highest end tables tend to have servos, so I wonder??? Also, when I last thought to do this, I was married to the idea of Mach 3. Now, I am thinking possibly LinuxCNC. I thought about CandCNC interface to make the learning curve shorter and have support. I am also amiable to the idea of a light industrial controller syetem, but I do not know how to evaluate that yet, or how to source one. Last i was considering all this, I do not remember anyone doing that. Again, I will likely do some industrial espionage and flatter the masters by copying what works well.

For rails, I would lean toward linear rails at this point, but I have not done my diligence yet as to the quality of the cheaper rails nor the price of high-quality rails. If linear rails get disqualified, I will probably use hardened rails with double-v rollers; although I see no reason the linear rails won't be a good fit.

I did read on an old thread that a company changed to genuine Hi-Win rails because the good cheaper linear rails were inconsistent for hole placement, etc and it hurt their manufacturing process and probably parts replacement. For me though, I don't think that is an issue as I just need a quality rail once. If I put that many miles on it, I can go through a little extra effort to replace the rails. Also, things may have changed with manufacturers since that thread.


-Mike

[acourtjester]

OK I wish to comment on some of your concerns (1) speed on Hypertherm manual I could not find any material the you need any more than 500 IPM and that was 26 Ga stainless mild steel is about 350 IPM. (2) A servo motor offers more efficient current control because it only uses the current it needs. One thing that a stepper motor is better at is its ability to generate holding torque at zero speed. Servo motors use more power to generate holding torque. There is no great leap forward using servos except cost. (3) Legs if your worries about 3X3 3/16" holding up your table put 6 legs on it. I think directional bracing to stop table wobble is more of a concern. (4) Linear rails and bearings I use roller bearings as they are easy to buy and are easier to replace if needed, and keep clean. I use 8 ball bearing on the X and 9 ball bearings on the Y sliders.

X slider test fit (13)A.jpg

X slider test fit (3).JPG

X slider test fit (4).JPG

[SegoMan DeSigns]

The exception to the servos not holding their position is the Teknik SDSK servos, they will hold the position with the max torque the motor is rated too. That was part of the "need to have requirements" for mounting an air drill to the gantry:

Teknic Vid




Tom and I are both sprocket heads when it comes to linear motion, the use of a rear drive line allows you to only use 1 larger motor vs 2 synchronized motors. Adjustment slots on each side allows squaring of the gantry. Table size is unlimited with this economic drive system. I used C.R. Rails as it was a budget build when they go they will be updated to the Hi Wins like you noted.

Here is a vid of the construction phase of my table it has been in use for 2 years+ the only wear item replaced on the linear motion was the idler sprockets used for tension on the drive chains, I used #40 roller chains for drives and #35 for gear reduction. Nickle plated was chosen for corrosion reduction.



Tom,

Are you familiar with this system? it is used on the mini drag racers for the kids: the advantage to it is once the hub is mounted you can replace the 2 piece sprockets without having to pull shafts, there is a large number of tooth choices as well. This is the link to the mfr site however you can get free shipping from Jegs on a some orders (small sprockets are ordered from surplus center as they have a better variety of shaft sizes ):

https://www.jrracecar.com/sprockets-and ... red&page=1

Steve

[SRdesign]

Ok, interesting that the 4x6 1/8" wall steel was no heavier than the aluminum 3x6. I will probably use steel. I will see if I can find out the samson gantry wall thickness. That machine screams at a 1000 IPM cutting speed capability. Would love to bump into one of those for a song. About 3 years ago I saw a 4x4 Plasma cam table from a high school that never used it for $750. My Dodge Diesel had caught fire 3 days earlier and I just didn't have my head on straight and I decided not to get it. Kicking myself since.

What do you think about ease of loading/unloading of a plasmacam vs. the tables with the rails down below the tabletop height? I had in my mind to extend the rails past the end of the table also, so I can have gantry well out of the way for loading/unloading steel.

I have a bunch of 3"x3" 3/16" wall for legs of table, so I am hoping to incorporate it.

Once I have a fairly lightweight solution, I will see what electronics are needed to move it. I have the idea of steppers with a 3:1 reduction for detail and rack and pinion. This is based on my thinking a few years ago though. I have never looked at servo electronics because it was out of my budget before. I am not sure what the fastest cutting speed I would use, so I hope to match the electronics to be able to do so. I cannot imagine 1000 IPM like that Sampson, but I am ignorant at this point. It would seem that I will not need servos to have fast cutting speeds; but I have noted that the highest end tables tend to have servos, so I wonder??? Also, when I last thought to do this, I was married to the idea of Mach 3. Now, I am thinking possibly LinuxCNC. I thought about CandCNC interface to make the learning curve shorter and have support. I am also amiable to the idea of a light industrial controller syetem, but I do not know how to evaluate that yet, or how to source one. Last i was considering all this, I do not remember anyone doing that. Again, I will likely do some industrial espionage and flatter the masters by copying what works well.

For rails, I would lean toward linear rails at this point, but I have not done my diligence yet as to the quality of the cheaper rails nor the price of high-quality rails. If linear rails get disqualified, I will probably use hardened rails with double-v rollers; although I see no reason the linear rails won't be a good fit.

I did read on an old thread that a company changed to genuine Hi-Win rails because the good cheaper linear rails were inconsistent for hole placement, etc and it hurt their manufacturing process and probably parts replacement. For me though, I don't think that is an issue as I just need a quality rail once. If I put that many miles on it, I can go through a little extra effort to replace the rails. Also, things may have changed with manufacturers since that thread.


-Mike

Yes, the 3x6 aluminum profile is heavier than the 4 x 6 x 1/8. 3x6 aluminum is what I used, it is heavy… think 60lbs. The reason I used the aluminum profile is because I didn’t want to drill and tap a bunch of holes for my linear rail or weld my gantry tube. Not that there’s anything wrong with welding your gantry together, I just didn’t want to go that route. It is bolted to the aluminum gantry side plates. The manufacturer you were referencing was star lab. They switched to hiwin linear rails. Acourtjester is spot on about cross bracing. 3x3x 3/16 is big enough on your frame. I bought all of my hiwin rail from https://motionconstrained.com
The cost of hiwin rail has gone up significantly since I bought mine. Here is my receipt for my order. They were the cheapest vendor I could find at that time.

3C41271D-D70C-461E-A02C-B9DFD3195F2E.jpeg

[acourtjester]

Segoman that is one slick table, I have a different design for the cross tabel drive. but the same concept. My cross shaft is inside the Y rail tube.
Those linear rails can get expensive, DIY guy like me cannot afford them. I like all the neat dodas you put on your table, little time drawing and cutting adds some flare to the table (eye candy)

DSCN4096.JPG

[mikeysp]

Reference the chain and sprocket, I am interested to know if distances change pretty frequently under heavy usage? While it probably is not as stressed as a chainsaw or even a bicycle chain, if running hours, it would seem that this would affect the accuracy?

[mikeysp]

Steve, reference that drain seal in the "Pele Goddess of Fire" video: Does the table have a lot of hours or is that a proven design? I ask because I consider slag possibly affecting the seal.

[acourtjester]

I have not seen and change in accuracy with my setup (chains) there really is not that much weight being moved around with either plasma or router operations. I also have adjustments that can be made at each end of the chains for the original setup of the table for the X and Y square alignment.
The chains are completely supported the full length of the rail so no droop or flop while moving about.

DSCN4102.JPG

[SegoMan DeSigns]

Mike,

The table has 2 yrs + usage on it and it works great, the drain now has a cover over it that prevents the dross from building up around the seal.I use a wet or dry vac to keep the slag trays clean.

I went with a pump transfer design for a couple of reasons, the first being I had a "never been used" 3hp 240V / 3 phase jet pump donated to the build and two I was unaware of the cheaper rust preventives at the time. Plans were to build a separator / filter system to prolong water changes.

The pump is nice as I can circulate the tank prior to draining it at water changes. The bladder / pressurized system is your best option.

When I changed my idler sprockets I noticed very little if any stretch on my chain that gets a good workout;

Main / Master link:

20180731_142303~2.jpg

Bracket with all way adjusting slots to attach to gantry skate:

20180801_134049.jpg

Idler Yoke:

IMG_2261.JPG

Tensioner Assembly:

IMG_2253.JPG

Urethane bushing tensioners for the chain:

IMG_20220407_152502832.jpg

The chains run in a plastic groove to prevent sag which would equate into backlash

Here is another spinoff design to the rear drive assembly with with belts:

[mikeysp]

Reference Cut speeds: If the samson can cut at 1000 ipm (for example) but the max speed my hypertherm 85 would use according to the cut chart is less than half that, what are we to make of this ability?

Me Speculating:

a. If it built to handle such fast speeds, it can with little effort handle the half of that for a nice smooth arcs and direction changes equating to very good cuts?

b. The cut charts are designed for the wide variety of tables out there, so with experimentation, one could increase power and cut faster than the charts with the same quality cut in theory?

c. both a and b?

d. other?

[mikeysp]

what is the advantage of the sprocket/chain compared to rack/pinion? Cost? What is the disadvantage?

[robertspark]

@mikeysp

a) it depends what the acceleration is how good the cut is


b)
85a is 85a.... good luck making it bigger.
cutting faster tends to lead to rounded corners (acceleration)

[SegoMan DeSigns]

Mike,

The cut speeds of 1,000 in / min is a magical pie in the sky number, your cutting with plasma not a laser, You will want traverse speeds in that range but your not gonna cut at those speeds. Stick to the Hypertherm charts and you will have good cuts. Start yourself a list and start pricing things out the Hi Win rails are going to be in the $3,000 Range. Chain and sprockets is the cheapest way to go and is still accurate, Belts are higher than chains (and melt if hit with sparks) R & P is even higher.

You stated you were wanting a 5x10 be sure to add room for the length of the skates and a little over size on the sheets. the rails are a max of 4,000 mm that's a tad over 13' Id say do that for the long side and 2,000 - 2500 for the short side. I left room to park my gantry off the cutting area as I did not want to bang the gantry landing a heavy sheet of metal. Your 85 puts you in the heavy metal club as well.

What do you have for drawing software? start laying out your machine, by the time it's done you will know how to use it. The rails below the cut table is a preferred system when using a forklift. One thing you need to do is start a book on your build save drawings, wiring diagrams, where you got what from where ect.

Is the big picture starting to develop yet

[adbuch]

Mike,

The cut speeds of 1,000 in / min is a magical pie in the sky number, your cutting with plasma not a laser, You will want traverse speeds in that range but your not gonna cut at those speeds. Stick to the Hypertherm charts and you will have good cuts. Start yourself a list and start pricing things out the Hi Win rails are going to be in the $3,000 Range. Chain and sprockets is the cheapest way to go and is still accurate, Belts are higher than chains (and melt if hit with sparks) R & P is even higher.

You stated you were wanting a 5x10 be sure to add room for the length of the skates and a little over size on the sheets. the rails are a max of 4,000 mm that's a tad over 13' Id say do that for the long side and 2,000 - 2500 for the short side. I left room to park my gantry off the cutting area as I did not want to bang the gantry landing a heavy sheet of metal. Your 85 puts you in the heavy metal club as well.

What do you have for drawing software? start laying out your machine, by the time it's done you will know how to use it. The rails below the cut table is a preferred system when using a forklift. One thing you need to do is start a book on your build save drawings, wiring diagrams, where you got what from where ect.

Is the big picture starting to develop yet