[dhc]

you'll find plasma is a walk in the park comparitively speaking... mines a dual purpose and i never could figure out art cam...

while im on the subject, do we have any experts on CORELL 10 in the group?

i have a minor irritation when i draw out a cut and export the DXF from corell.

basicly what happens is my "nodes" develop mind of there own and are fine on my version but once i convert to dxf ( in corel ) they are not where i put them! most are but i like to cross my start & stop points to assure a complete cut and occationally the nodes move...( this is not a "snap to" function it's something entirely different and weird)

[Scott V]

dhc,
go here and ask Tom about your Corel issues.

http://tinyurl.com/9ghxm
Scott

[justin]

dhc,
Sorry to hear about your trouble with practical, I purchased a 4x8 router & Plasma from them. I am doing both routing & Plasma with mine. What problems are you having? My table is wobbly which I will be fixing once I have come cash. Right now it is hard to rout a good circle in aluminum, I always seem to get a bit elliptical. I also would like to hear from other practical owners. Maybe someone could start a forum for practical owners to share tips?

Cut more,
I have a PCNC machine as well. The eliptical problem is re-occuring. All of the set screws seem to loosen up on the motor shafts. I have disassembled the whole machine twice and re-tightened everthing! Another PCNC owner that lives close to me has come up with a kit to solve most of the issues that he feels is wrong with the machine. He drilled and pined all shaft connections??? Hope this helped.

[cut more]

Justin,
Thanks for the info. Did you drill & pin the motors on your table, and if so did it fix the ellipse problem? What else is in the other practical owners kit?
Thanks

[justin]

I have not done it myself, but my buddy Paul has and it worked. He also has the additional lower v-rail that runs up the y axis. When I tighten things up, the problems go away, but it only lasts for a week at the most. Paul is suppose to come and fix mine like his, when I get some more info, I will let you know.

[rherman]

I have owned a PCNC table for routing for over a year now. I have cut my boat kit parts with it, some korbels and some 3d work; however, I have to agree about the service. I spent a good deal of analysis on their table design coming from a mech and pt background. The shafts are undersized for torsion deflection and they have necked down a 3/8" shaft to 5/16" to fit the pinion. They should have bored out the pinion and cut a key for it instead of set screws. Also, any turning down is not radiused to spread stress on this stress point. I could go on, but the only problems I have had so far are the x-gantry idler shaft pulley is pulled too tight by the spring, anb they only made one groove to receive one of the c-clips and the other is just a friction fit on the shaft. I can not cut mirrored arcs that match by cnc standards. I read a few posts back about elliptical circles. I found that the steps setting in my WinCnc.ini file for the x and y axis were different, eventhough they appear to use the same pulley ration and pinion diameters. Why? Also I can cut a 100k gcode file with no arcs and the machine homes reasonably well. If that file has one or two large arcs in it, it misses coming back to home by over 1"! This is the x-gantry problem rearing it's ugly head. I am now looking into retrofitting the entire table myself with bigger shafts, keyed pinions, Mach2 instead of WinCnc. I would be interested to hear if anyone else is interested in the Mach2 conversion. It should boost my 3d part cutting speeds using Mach2's CV feature. I have to say compared to the $180K table at my old job, a 4'x8' router table for under $10K is still good, but not good enough for a busy production schedule. Thanks.

Rob

[Scott V]

I got all the stuff for mach 3 change over but I just have not had the time.
I am only doing plasma with this table so 3D does not matter to me.
I would like to know of any upgrades to the table that you guys come up with.
Shafts and rails like the y rail interests me the most.
I do get excellent circles out of my machine.
If I use sheetcam and the latest patch for corel 12 (HPGL)
it really works fine. My stuff has stayed tight but I am
sure with a router it would get pretty ugly fast.

[cut more]

I read a few posts back about elliptical circles. I found that the steps setting in my WinCnc.ini file for the x and y axis were different, eventhough they appear to use the same pulley ration and pinion diameters. Why?

Rob,
I have talked to Josh at practical in the past on my elliptical problems. The probable reason for the different setting in wincnc.ini is you need to send each axis a certain distance ie. g01 x48", then measure the actual distance travelled and adjust the step setting untill you are dead on. About the cutting arcs and not coming back to same place, I have noticed the same thing with plasma cutting, sometimes I will have to stop during the program and re-home the machine then continue the program. Any one else have that problem? and could it be missed steps?

[justin]

I have the FlashCut version, and haven't had any homing problems. I was wondering if any of you experienced people have herd that you can tell which axis is causing the problem from the eliptical circle?? Joe told me that if you get flat spots in the x direction, the y axis is the problem, and if you have flats in the y direction, the x axis is to blame??

[rherman]

justin and cut more,

What josh talks about in setting the resolution is correct; however, considering the same pinion and rack and stepper are on each x and y axis, the resolution should be the same. I used a dial indicator and was getting repeatability to .002" after moving 12" away and towards the axis I was setting. This is the way I do if for my metal machines. His method is an infinite series method. Either way you should be able to use the dial indicator to verify. No, my arc problems I believe are due to two design flaws. I have slowed down cutting speeds and reconfigured my wincnc.ini file to make sure I wasn't missing steps. One the shaft on the y-axis is 3/8" necked down to 5/16" to accept the pinion gear. They should have used at least a 1/2" shaft and bored out the pinion to accept either 1/2" or a neck down of 3/8". Over this length of shaft with torque, the table can rack to torsional deflection of the shaft. Second, they placed an idler shaft on the x-axis timing belt. With positive engagement belts, not v-groove friction-types, they should have simply slotted the motor mounting holes so you could tension by hand and then tighten down the motor bolts. Plus the spring is way too stiff. I forgot to mention that the plastic bushing on the idler shaft is captured by two c-clips; however, only one has a receiving groove for it on the shaft. The other one is simply snapped on. If I had the time, these are the modifications I would make:

Use 1/2" shaft with keys instead of set screws.

They sent me the under carriage hold down vee rails after I pointed out the router jumped. I'm not sure this is std. on their machines now. I bought mine over a year ago.

Shorten the distance on the x-axis shaft. It is seriously overloaded to bend without a bottom capture point.

If you don't need the torque, but need more speed, swap the pullies and belts for a 1:1 ratio. Currently it looks to be about 2.75:1. You will have approx. 1/3 the torque, but 3x the speed. You could buy bigger steppers also.

My frustrated 2 cents.

rob

[cut more]

reconfigured my wincnc.ini file to make sure I wasn't missing steps.

rherman,
Thanks for the info,how did you reconfigure your wincnc.ini to make sure you did not lose steps?
I like the idea of slotting the motor mounts to tension the belts I will look at that tonight.
Looking in MSC catalog, they offer keyway broaches & bushings all the way down to 1/4" dia. x 1/16"key. I think I will try that with my pinions & shafts.
My table came with the x axis under carriage v rails, this is supposed to be standard on their tables now.
Anyone know what size steppers we could go up to with the practical drive setup?

[tmechanic]

I'd like to know about how your conversion goes, I'm planning on building my own table based on the PCNC table and am interested in hearing how the Mach3 works with this configuration.

[rherman]

Also, on the y-axis under the covers, there is a similar idler setup. I am looking to see what the closest belt size is that will allow me to get rid of that idler as well. I'm sure there will be slack, so I'll have to see if slotting holes is possible there as well. If not, at least less of an idler indent into the belt. I meant that I put my wincnc.ini file back to values in accel and vel that were very slow just to test the resolution and use my dial indicator. Once I did that I bumped them back up and retested with the indicator. I am now running the table without the idler shaft on the x-axis. No problems. That belt was tight without the spring and idler shaft. It seems fine and now there's less tension on that puny shaft. I would recommend looking into bumping up the shaft to 1/2" before replacing the pinions and putting keys in. Just because it doesn't slip, doesn't mean it will not exhibit torsional deflection seeing how wimpy that long shaft is. Good luck.

rob

[LaserCNCman]

Practical CNC has improved the engineering that has been the problem
with their tables. Subsequently the tables made by Dave Cress and Dyna
CNC are made from the stolen blueprints he took from his breif
employment at practical CNC. Very fortunately the stolen information
was the problemed areas. Now the only tables to enploy this ineffective
system are the Dyna CNC tables. The new Practical CNC tables have been
remade with all of the features that make a $60,000.00 machine. I now
own two Tables one plasma & one router, despite a few kinks when
setting up, (which I also had with my Camtech $60K table)The table
works flawlessly now! This web group seems to be setup so that Dave
Cress and his few friends can bash the company they stole all of their
ideas from. Thankfully that crappy Tinker toy technology was dropped by
PCNC and only Dyna CNC has to deal with it now. Good luck and have a
nice life! Cheaters never prosper!
:boxing:

[LaserCNCman]

there is only one Practical CNC, all the others are just imposters!! sorry WANNABEES!!

[Scott V]

We are Practical CnC owners so there is no reason to try to give us a line how
wonderful a practical machine is now. Please take your advertisement
somewhere else because nobody is buying your line of stuff.

"Now the only tables to enploy this ineffective
system are the Dyna CNC tables''

You mean there was problems with the practical tables??? I would of never guessed that!!!!

[Scratch]

Wow Lazerman, nice first impression.

First off...
Hi and welcome to "How to Use Internet Forums Class 101."





You just failed.

[Mariss Freimanis]

They're a class outfit alright. They stiffed us for $6,000 worth of drives.

Mariss

[Scott V]

They're a class outfit alright. They stiffed us for $6,000 worth of drives.

Mariss

I think LaserCNCman has just opened a huge can of worms for himself!!!
(chair)


Mariss,
you are a better diplomat then I would/could be!!
I only got stiffed for a pile thc and no home switches.
I heard that the home switches were of a quality,
that it really does not matter if I got them or not.

I will say I am very happy with the drives in my unit,
and I hope they were the paid for ones. They are some of
the things I like (feel good ) about my table. I also watch/check
the temp to see if they are going to cook from lack of
heatsinks. Something you told me to look out for.

Thanks,
Scott

[Scott V]

I had a visitor to my shop today. Dave Cress of DynaCnc was in
town and wanted to stop by to say hi. He brought Mark along. one
of his employees with him to see a practical machine.
They were both polite and did not feel the need to bash
my table. It's probably because we are on the same page
as far as reality.

Anyway, It was good to pick his brain on a few things
and Mark just quietly did the things I would do, if I was
checking out a table. You know like put your hand on the
gantry to see how smooth your unit runs.

He had to run because another Practical Cnc table
owner wanted him to stop by and see he setup.
Seems to me, Dave does more suport for the practical
tables then practical does. :cheers:

I do know that Tom Caudle/ Les at Sheetcam and others have
helped me way more then practical cnc ever did.
If it was not for those guys I would of hired somebody
to program my table to cut itself into small pieces!!!

Hey LaserCNCman,
are you Joe from Practical CNC?????