[keastab]

I was wondering what advantage in stiffness a 2" x 4" x 1/4" rectangular tubing was over a 4 inch C channel on a 4' cutting Width "Y"(56"-58") would be?


I just got done with my Solsylva 24" x 48" and was pleased as all get out with it for what I wanted to do
so this might be a long post.
I vacuform some things and it cuts the outside shape out LOTS better than I ever could(really I'm worse than you can imagine!). Any way the Wife got involved in a discussion with me ( asked what it could do. I told her LOTS, but SLow due to the Allthread that I used and even the later 1/2" -10 acme). She saw a youtube video of cabinet making and decided for me to build her a cabinet over 3 foot wide 72 inched tall! She has wanted for a while. $%% ??? it won't fit my machine . so I tell herI'll have to upgrade to a bigger machiine. yup cost came up then. I saw a user on here that had built a V bearing machine from solsylva and thought it would scale nice in the X direction but might give me a fit in the Y, I contacted the Author of the plans and he said scaling up x "no problem" Y requires a bit more. I like his design a lot. If will go on a welded steel frame table made from 2" x3" x /14" tubing and laser squared by a friend at a machine shop so that's taken care of but the "Y" problem still bugs me. so does rectangular thick wall tubing (capped with 1/2 plate and TIG welded solid on the ends so I can thread it to the gantry plates) seem like a viable option? the particulars of the electronic's are a 4 axis Gecko g540 48v, 380oz steppers kit from CNCrouterparts. the x will be rack and pinion with a mid mounted stepper and 2 outboard pulleys running the pinions shown in the picture that I hope shows up. right now it's drawn up as a 6" c channel and the author has some reservations on it due to my low 380 oz stepper motors. I like the simplicity of the design and also the fact that I can do 99% of it except for the leveling/squareness of the steel table and tig"ing the end caps.

any input would be appreciated on the differences in c channel vs square tubing. and suggestions on a work around

thanks

Ps I'd love to have been able to get a "kit " for this but it's just not in the budget for me and I LIKE working on stuff to make thing work. I built a proto form Vacuum former and kicked it out to a 2' x 6' size so I could make my obsolete car parts since no one make many parts for old dodge dart convertibles. (plus I want to make creature comfort parts for the convertible like built in cup holders,power centers on the custom console,door panels to replace my old ones since I have power windows instead of cranks, and speakers so that you can really hear music from more than the dash speaker)

[Devastator]

I'm planning on doing the same thing with my Solsylva except that I'll either be using a wood torsion box or a mongo laminated wood beam for the gantry. My build is wood with some strategic placement of steel angle iron so I will probably continue that concept. I'll be tuned to your thread, for sure.

[keastab]

I though about just upgrading the 24x48 unit BUT I like the v bearing design because it locks the gantry onto the rails and rack. another plus for me is less cable routing since all the motors will be ON the gantry. 1 cable way, THAT part I like. if I do 6" c channel then I'll have to modify almost the complete gantry system to expand it to a 4 foot cutting area. that means going to L style pulleys ,3/4 belts and man are they BIG! or run 2 nema 23 motors slaved to the X axis. also I have to talk to the CNC routerparts guru to size the motors(AND CONTROLLERS) correctly to the enlarged size of the gantry. I'd like to push it 200ipm or better(I want to be able to do acrylic for sure too!) but I'm not sure it will unless I change motor size. that's one of the reasons I was asking if 2"x4" rectangular aluminum thick walled tubing would be a better choice for the center beam than 6" C channel. so far I've got 4 square foot of .25 flat aluminum plate for the side gantry plates, the r6(y axis shaft) 3/8 2 start with backlash nuts and r8 bearings Racks and pinions sized for the 1/2 rod I'm using to move the gantry along the X. V bearings are on hold until I get more cash to work with. it'll get done since the Wife get's what she's been wanting for a while (and if I want to stay happy,) because the other choice is really miserable for me to think about.

[Devastator]

Yes, if I had to do mine over again I would choose the V bearing design. I didn't even see that as an option when I ordered my planset. When I expand mine, definitely going with two motors on the X, still using short drive belts on the lead screws though. I initially thought the belts were a bad design, but they do make it so that there are no special spring type couplers like on direct drive, and they also help decrease resonance if you don't have a better driver that compensates for it.

I don't see why you wouldn't be able to do 200 IPM. My current machine can rapid @400 IPM and my motors and driver are low budget hobbycnc stuff. With a rack and pinion setup, I imagine you could even go faster. I'm sticking with leadscrews because I'm doing a lot of small fine engraving lately, that I can't imagine a rack would give enough resolution for.

My guess is that your rectangular tubing may not be as rigid in torsion as a C channel, but I defer to brighter minds on that.

[keastab]

Yes, if I had to do mine over again I would choose the V bearing design. I didn't even see that as an option when I ordered my planset. When I expand mine, definitely going with two motors on the X, still using short drive belts on the lead screws though. I initially thought the belts were a bad design, but they do make it so that there are no special spring type couplers like on direct drive, and they also help decrease resonance if you don't have a better driver that compensates for it.

I don't see why you wouldn't be able to do 200 IPM. My current machine can rapid @400 IPM and my motors and driver are low budget hobbycnc stuff. With a rack and pinion setup, I imagine you could even go faster. I'm sticking with leadscrews because I'm doing a lot of small fine engraving lately, that I can't imagine a rack would give enough resolution for.

My guess is that your rectangular tubing may not be as rigid in torsion as a C channel, but I defer to brighter minds on that.

hmm good call on the belt issue. I like the way it's easy to setup in different configurations. BUT since I'm only going to do my LEd circuit board occasionally the rack and pinion should be close enough(in resolution) to drill the holes and total overall shape for the 4 leg lumileds. I'm not "learned enough yet to go SMT yet. Well so far I have drawn the gantry up in 2"x4" tubing, the original 4 " c channel (good to 3 foot from the author) 6" c channel lot's of rework there. and finally in 4 " I beam. I atually Like the I beam concept but still do not know which is better for a 56" gantry
2"x6" rectangular thick walled tubing
6" C channel or
4" I beam
All are aluminum and as thick walled as I can find.
someone should have already explored this concept but all my searches come up empty or related to a STEEL I beam or box frame.
here's the I beam setup so far.
I'm still working on finding the measurements of the Rack gear height for 20 degree racks so I can properly locate the shaft that the spur gear will ride on but it's getting closer to a workable unit

Attachment 226914

[keastab]

ok I've look around and found out a lot of good info. I have decided to go with the 6" x 2" rectangular tubing as a gantry system connected to .5" plate sides. I'm having the inside thickened on one side with a 4"x 60"x.5 " inner strip that I can tap for threads to hold the angle iron on for either rack and pinion or acme. after it's tacked to the inside of the tubing I'' have the end caps welded with a .5 inch plug. that should sturdy it up and hold my rails for the Z . I'm using a belt and pulley system to power the pinions for the rack and pinion setup for the X. I wanted adjustments to the belt system and have not yet finished the setup. but since I used the setup on my first solsylva and ended up with over 3 inches of movement for my long belts in the adjustment area I'll use a similar but smaller. the belts should be relatively small (except they are "L" pulleys I'm using to fit on the .5" power transfer shaft.)

[manofmanyhats]

I'm very interested in this. Have you come across anyone else that built the V-bearing machine? I wasn't able to, so I posted a build log here last year of mine. I kept it mostly stock with a 2x2 cutting area. I'm probably going to expand it to 4x2 shortly with an overhang and permanently mounted rotary.

[keastab]

I have not seen any threads of the v bearing setup except one and it might have been yours that
I watched. so far it's a different experience in designing it for a 4' x 8' cutting area design. I have to scale up the strength and stiffness to accommodate the 4' cutting area so it'll be a 55" wide design.
going to the rectangular aluminum tubing has made some changes and scaling sort of hard until my pinions and "L" class pulleys come in. (dang they are huge!) it's be a mid gantry mounted X axis motor 15 tooth to a 15 tooth pulley (centered on a shaft. on the shaft there will be a 36 tooth pulley to a reducer shaft that holds the pinion pulley , I'm also giving me the option to use 2 steppers to work the X axis by rotating the Y' axis stepper to the front side of the tubing and letting both X axis steppers be on the back side of the gantry(that another side plate option I'll have to design up. so far I have cut the side plates from cutting board material to check setup fit and am waiting on parts to arrive to double check my measurements of the shaft to pinion to Rack position.

[keastab]

I've been slacking off a bit (burst appendix really slows ya down) and was unable to get much done. BUT that's changed for a bit, I just cut a test side panel out of the free acrylic I got. Just to test the measurements against real life. I've discovered that :
1. I probably can't measure worth a darn.
2. or I have my calibration off a little bit on the CNC ( number one is more likely but ya never know)


anyway here is a test side plate using the v bearing setup (yup pinion bearing has to be moved to work with the rack) the other stuff works pretty good though.
v bearing setup.
Attachment 240520

I can even tension the belt!!!
Attachment 240522

now to drill out the y axis pulley to 3/8th for the 2 start screw.
Attachment 240524

and of course my goof. glad it's in plastic test instead of aluminum
Attachment 240526
that looks to be about .125 up to get the pinion shaft into position to clear the 3/4x1/8 guide rail and still be able to mount the rack into position to fully engage the pinion.(hopefully)

so I'll adjust for that 3/16 up and see what works!

[keastab]

oops double post!! (fat thumb)

[keastab]

Just got a little checking done on the plastic prototype and so far everything looks good to me.. now I know where to drill the mounting holes in the rack to clear everything. 1 step closer to getting it in aluminum!!

clears the gear, that was my main worry whew
Attachment 240662

got good engagement too!
Attachment 240664
it even Adjusts!
Attachment 240666

now I can get to drilling the mounting holes to square it all up!
Attachment 240668
clearance for the front bearing too! yahoo!
Attachment 240670

[paxx]

@ keastab, did you make more headway with this modification? I am looking at doing much the same thing and am interested in what you have shared up this this point. I have all of the solsylva plans and really like the v-bearing, but want rack & pinion on both X & Y in a 24x48 size. Kinda of 24x48 R&P model with the v-bearing mod with the v-bearing base as well.

Love to see what more you might have done.

Paxx

[keastab]

@ keastab, did you make more headway with this modification? I am looking at doing much the same thing and am interested in what you have shared up this this point. I have all of the solsylva plans and really like the v-bearing, but want rack & pinion on both X & Y in a 24x48 size. Kinda of 24x48 R&P model with the v-bearing mod with the v-bearing base as well.

Love to see what more you might have done.

Paxx

I've got the side plates done up in HDPE for testing purposes and everything seems to work the way it's supposed to. I even made the right measurements on the gearing/rack offset (Yay me! I got it right the first time, A rarity)
I have the Aluminum ordered to size Except the 6 inch C channel. that will be ordered after I get an exact sizing so that it's cut square by THEM and not by me. mine will be (for now) a nema 23 (a gecko g540 setup) 44" x 72" model.

late next 2016 I'll be setting up a second machine for larger projects. if my savings go as planned. and still using the v bearing setup for the X and Y.
a 3" square steel tubing table for the 5' x 9' table using Chinese spindle,American VFD, nema 34's with corresponding gecko 's and breakout board to move it rack and pinion on X and 5 start on Y & Z , hopefully it will be sturdy enough to take the plywood cabinet cutting I intend to do.

[paxx]

I've got the side plates done up in HDPE for testing purposes and everything seems to work the way it's supposed to. I even made the right measurements on the gearing/rack offset (Yay me! I got it right the first time, A rarity)
I have the Aluminum ordered to size Except the 6 inch C channel. that will be ordered after I get an exact sizing so that it's cut square by THEM and not by me. mine will be (for now) a nema 23 (a gecko g540 setup) 44" x 72" model.

late next 2016 I'll be setting up a second machine for larger projects. if my savings go as planned. and still using the v bearing setup for the X and Y.
a 3" square steel tubing table for the 5' x 9' table using Chinese spindle,American VFD, nema 34's with corresponding gecko 's and breakout board to move it rack and pinion on X and 5 start on Y & Z , hopefully it will be sturdy enough to take the plywood cabinet cutting I intend to do.

That sounds like things are going in the right direction. Smart to let them do the cutting of the c-channel. Hope you keep us updated on this thread as you make progress. I am going to build a smaller Solsylva as my 1st so that I will be able to use it to drill/machine the flat aluminum pieces of the next bigger one that I plan on doing. I too am going to go with nema 23's and a gecko 540 that I will move to the larger modified Solsylva that I end up doing. Gonna slightly modify the 1st one I'm doing as well. Plan on v-bearings on all axis, and some 5 start as well. Also going to laminate hardwood ply, like birch or such, instead of using dimensional lumber that will end up twisting as the temps/humidity changes. Also will stiffen the gantry and x-rail supports with angle iron along top and bottom to stiffen and give more substance.

Anyway...thanks for the reply. Looking forward to more pics and info.

Paxx

[Devastator]

Also going to laminate hardwood ply, like birch or such, instead of using dimensional lumber that will end up twisting as the temps/humidity changes. Also will stiffen the gantry and x-rail supports with angle iron along top and bottom to stiffen and give more substance.

I did exactly that. Don't forget to buy a router bit with bearing to radius your beams because the angle iron has a radius on the inside 90.

[paxx]

I did exactly that. Don't forget to buy a router bit with bearing to radius your beams because the angle iron has a radius on the inside 90.

Never thought of that. Luckily I do have a great set of router bits with several quarter round sizes with bearings. But nice to know before assembly!!! Thanks for the headsup!!

Paxx

[Devastator]

Never thought of that. Luckily I do have a great set of router bits with several quarter round sizes with bearings. But nice to know before assembly!!! Thanks for the headsup!!

Paxx

No problem. Also, even with a bunch of screws in the angle iron, it can still twist independent of the beam on the gantry. I bonded mine to the beams with epoxy in addition to the screws.

[paxx]

No problem. Also, even with a bunch of screws in the angle iron, it can still twist independent of the beam on the gantry. I bonded mine to the beams with epoxy in addition to the screws.

That is a great idea and had thought of that.........now....... I may not have remembered? Thanks for the reminder!!

Paxx

[keastab]

No problem. Also, even with a bunch of screws in the angle iron, it can still twist independent of the beam on the gantry. I bonded mine to the beams with epoxy in addition to the screws.

That's what I will be doing with the top and bottom 3/4 angle on the C channel for my newest upgrade, I'm using automotive panel bond instead of normal epoxy though. It's really a complete rebuild to a different spec. I have my gantry side plates made up in HDPE and bearings inserted to double check myself against screw ups. so far so good. I do have the metal ordered to size and am waiting for that bunch to come in and me to machine it so that I can finalize the C-channel sizing.
It looks to be a 44"x72" to accommodate all the plastic abs parts I am making right at this time.

here are a couple pic's of it(gantry side plates that is) assembled in HDPE for testing. it's close, real close to the rack about 135thou clearance from the c-channel to the rack I might have to clearance it somehow if it wears the rails significantly or the c channel is not the dimensions that were given to me.


got the wrong belt #$#$, needs to be a liiitle bit shorter 2-4 teeth so I can get full adjustment for stretch once I make my aluminum or steel offset bushings. HDPE bushings just crush darnit.
Attachment 264678


If my C channel is bigger than the dimensions show then I will have to machine some off . it's that close about 130 thou or so.
Attachment 264680

next stop is adding set screws to the pinion gears and taping 10-32 setscrews in there.
Attachment 264682


I'll have to put a radial bearing on the shaft there for precise loading but a spacer will work for now till I get the final width of the machine.
Attachment 264684


I cut some silhouettes of the dimensioned C-channel to make sure I had clearance . I hope I got it right.
Attachment 264686


when I do the aluminum side plate for the stepper I'll make sure to recess it in .2 so I can get to the darn setscrew easier ^$%^ , I hope I don't forget to redraw it later.
Attachment 264688

[Devastator]

Looking good. These Solsylva machines can be really solid with the right upgrades. I've machined steel on mine.

One thing I wish I had done just for cosmetics is to cut the top front corners of the gantry endplates at a 45 degree angle. Mostly for looks, but it will save just a bit of unneeded weight.