[pminmo]

You guys are doing a bangup good job. Keep up the great work!

[DieGuy]

After visting the hardware store (OSH) I decided against the angle iron. It just didn't seem very straight. It seems to have weird kinks in it that could end up being a real pain in the butt. I also think the way we'd have to mount it would be silly. Tapping MDF doesn't sound like a good idea. But I really liked the square rail idea, so I looked at the square tube and thought it looked straighter in general. In regard to making the ribs for the torsion box: I think the idea of building one out of wood, aluminum, MDF... whatever, and using that as a template for a router to trace would be sufficient in providing a set of even ribs.

I like the square tube idea as well, the only issue is attachment but threaded rod run all the way across and a triangle shaped "washer" made from aluminum would work nicely. The hardest part is drilling a hole large enough on the corner of the tube to get a socket wrench through to tighten it all up. You could even double nut it to make sure it didn't loosen up over time. you might have to raise the bearing on the axle to clear the hole in the tube crown.

As far a using angle, I sure would not tap the mdf, I would cut a cross hole and drill through to it and place a half round looking "washer" and nut on it.

PS I love your rendering!

[ger21]

As far a using angle, I sure would not tap the mdf, I would cut a cross hole and drill through to it and place a half round looking "washer" and nut on it.

Instead of tapping the MDF, just use woodscrews. Drill and countersink the angle, and carefully predrill the MDF with the correct size bit, and screw it on. It might be a good idea to reinforce the MDF with CA, though.

[izzlestar]

Ok, I came up with another idea using angle iron, I thought that I would post it to see if you guys think it is viable. It is patterned it after the "shopbot" rails, except it doesn't use the dualV bearings. I think I found away around spending 20 some odd dollars a bearing to use angle iron. The "newrail4" image shows how the outside bearing holes can be slotted to allow the bearings to be adjusted. The inside angle iron (rail) is 1.5 inches and the outside angle iron (truck) is 2.5 inches. Enjoy! _Carl

[Rance]

I don't remember it hanging down like that... I thought it was tapped into the end grain so to speak.

Mike,

I agree w/you, it's best not to hang down that far. You may have missed it but his prolly works well because it is also deep lengthwise along the axis. It's not a plate, it's more of a square block.

Your attachment 'looks' as sturdy/sturdy enough. And also uses less material.

Rance

[dpot]

Hey Dave,

I like the idea! But I have a question. Do you have the capability of doing a quick 3d rendering? there are alot of people who have a hard time visualizing the 2d stuff. Also for the plans, if nothing else we could include this for an optional build idea.

Also what size angle did you have in your design? I believe it needs to be at least 1-1/2" for the large machine. I know the torsion box design is self supporting but I also know MDF. I only have a dxf viewer, no capability to see measurements. I really wish I was good at cad work. It would make sharing ideas so much easier.

Gerry,

What do you think about this? I like the idea of being able to add more than one bearing per axle to eliminate the wear tracks in the rail. I really think we are on to something here.

Everyone let us hear your opinions.

Thanks,
Jimmy

Hi Jimmy
Yes l can I have AutoCAD 14 and 3d studio that will render most 2d or 3d DWG.
My design has gone in a different direction to the Hardware store design CNC router
I have gone for 16mm liner rails all round 50mmx75mm steel main frame and removable
Torsion box design so I can jig each table for the parts to be routed I have attach a dxf of my router and if you can skesch a dwg in format (windows metafile tif gig bmp jpeg) with dimension on I can 3d it and render back in dxf wmf bmp. Wood be interested in a vacuumed design if Torsion box design if you have one It will be for holding down berich ply light ply and aly

[achiestdragon]

ok
sorry for another dxf in 2d
but i do seem to prefer the idea of using box section rather than angle iron

trying to use the dfx to show how it could be posable to mount it easy without the need to fish around inside it for nuts and washes

using screws , the holes for the screws can be drilled on the flat sides of the box , near an edge so as not to interfere with the part the the bearings travel on

i also have a thought about alignment , think i solved that also but need to draw it , not got time at moment , but will try to get it done later today (in 3d :S)

[achiestdragon]

ok rough 3d drawing of it attached

the box would be hollow box section , the two bits running parallel are mdf
and the bit sticking down is the cross suports of the tortion box also mdf
the bit sticking down is 1 of a number of pieces accros the lenth of the tortion box as the other designs have shown

sorry but not used blender in ages and could only get it to change the colour of all bits at once

using the mounting method like shown in my last dxf it would offer 2 advantages doing it this way
alignment should be posable if the mdf that the rail rests on is screwed to the tortison box , and the extra support would hold the rail accross its entire lenth

Dave

[mikeschn]

Wow, you guys have been busy...

Blender, what is that? A CAD package?

Is there anyway you could make those .bmp images larger, or change to a .jpg format?

The pipe design is nearing completion. I just need some kind of thrust bearing on the end of the acme thd rod, and a tool holder.

Any suggestions for the thrust bearing?

Mike...

[mikeschn]

Ok, I came up with another idea using angle iron, I thought that I would post it to see if you guys think it is viable. It is patterned it after the "shopbot" rails, except it doesn't use the dualV bearings. I think I found away around spending 20 some odd dollars a bearing to use angle iron. The "newrail4" image shows how the outside bearing holes can be slotted to allow the bearings to be adjusted. The inside angle iron (rail) is 1.5 inches and the outside angle iron (truck) is 2.5 inches. Enjoy! _Carl

Carl,

I really like your concept. I think it has a lot of promise!

Mike...

[ger21]

Blender is a free modelling and animation package.

[mikeschn]

What do you guys think of Steve's Thrust Bearing? It looks simple enough!

http://www.cnczone.com/forums/showpo...2&postcount=61

Mike...

P.S. Steve, can you tell me more about the bearings? They just slide over the 1/2" acme rod, right? Got a part number, URL or a source for the bearing?

[ger21]

If it works OK, it's by far the easiest way to go. Not the cheapest, but not too bad. How's it working, Steve?

[spalm]

Hey,
I really, really like it. The picture that is posted did not work and really shows how not to do it. I went with radial bearings and two MDF plates. If are you planning on a 1/2x8x2start screw, I’m not sure on tapping your own AB nut, but I never attempted it. I don’t have a good picture of the final towers, but I attached one that I posted earlier using 3/8x12 rod that I had lying around. The concept is the same, to quote myself:

“Leadscrew mounting can help three problems at once: whip, backlash, and motor wear. The trick is to “fix” the screw at the motor end and not let the motor’s bearings take any of the load while firmly attaching the screw to the frame. It takes 4 nuts, two MDF blocks, and two bearings in a configuration as in the picture. The MDF pieces form a thrust plate. The bearings sit in the recesses and are back to back. The procedure is to loosen the motor coupler, lock the two nuts nearest the motor together, and then tighten the next nut to compress the two bearings together against the thrust plate. Finally tighten the outside nut to lock it all together. Now tighten the motor coupler. Firmly attach this to your machine with nuts.”

To do the same thing with 1/2x8x2 you will need shaft collars and spacers instead of nuts, as nuts were not available. I attached a picture of my Z that uses this. In both cases, the two bearings are tightened firmly against each other to remove any leadscrew backlash. The far end is a single bearing that has either a nut or a collar that is then tightened to keep the screw in tension. I had to slightly “turn down” the OD of the screw with a drill and file to get the bearings to slide smoothly up and down the end of the screws.

Bearings MSC 3543390
Screw MSC 01205996
Collars MSC 87856779
Spacers were either hardware store Nylon or small sections of copper pipe.

I am probably going back to 12tpi for the Z so I can lift my heavy router easier. The other two axis are happy with the 4tpi screw.

Sorry for the ramble,
Steve

[izzlestar]

Ok well, I headed over to OSH and picked up some angle. The only problem was that the largest that they had was 2". So I picked that up and some 1" to use as the rail. The original called for 2.5" for the truck and 1.5" for the rail. After a little re-designing I came up with this. (attached) I'm really happy with them, I see a lot of potential... I don't mean to keep hammering you guys with this stuff, I'm just trying to contribute, even if it isn't using the torsion box ideas (which rock btw...) ...Anyways, the only problem with the idea is that if you try to twist the truck around the rail, it has some play. But I don't see that being a problem when two rails are mounted parallel... Lots of good stuff here guys! _Carl

[mikeschn]

Carl,

That's looking good. Please keep the ideas and the pictures coming.

Mike...

P.S. Are you going to add wipers to get the dust off the top surface of the angle where the bearing rides?

[Rance]

Mike,

To answer your question from the CheapCNC thread, yes, I do like the direction it is taking. I REALLY like the torsion box design with the rails on the inside (post #289). It leaves very little room for flexing. You might consider widening the table in the Y axis to keep swarf off the rail though. I believe it is superior to the JGRO approach, but they both have their tradeoffs. (I'm going with the rod rather than the angle or diamond.)

I'm gonna go back and review the entire thread but if you think you can really build the H/W Store machine for $200 that is great news. I could see the controller and 2 steppers costing that much. Don't get me wrong, < $200 is closer to my price range. Initially, working from the cost backwards for my own target machine cost of <$100, I ruled out even the minimal electronics to drive the average steppers(100oz/in?). With that, I chose to go with floppy steppers and just use their existing electronics. Consequently I'll have to scale the cabinet/gantry down to using scavenged printer rails, and bearings from old disk drives. This in turn limits my first machine's use to small wood projects and PCB etching, which I currently don't see as a problem.

Have you guys defined the target electronics for this machine? I would be VEEEEERY interested to find out if you all have found a way of getting around the high cost of the controller for this machine.

300 posts in less than a month... I think you guys have the target audience.

Rance

[mikeschn]

I haven't worked out the entire price for the hardware yet. I know we have 2 sheets of plywood @ $29
2 packs of skate bearings at $29 a pack
12' of pipe at an average of $3 per ft
tube ?
angle $10
hardware ?
acme thd rod ?
coupling?

So I am at $162 so far...

For the electronics, since I know nothing about electronics, I am going to suggest a 3 axis controller from xylotex for $145
http://www.xylotex.com/#3axis

3 steppers from ebay... figure about $100
http://cgi.ebay.com/SKC-NEMA-23-STEP...QQcmdZViewItem

A 24v power supply $39
http://www.web-tronics.com/dualout100wa1.html

A 24 v cooling fan $2.50
http://www.allelectronics.com/cgi-bi...209&type=store

So for the electronics I am at $287 so far.

Throw in a couple bucks for wire and connectors, and you're in business.

Your first project is to build a wooden enclosure for your electronics... I can't find the picture right now, but when I do I'll attach it here...

Mike...

[achiestdragon]

I haven't worked out the entire price for the hardware yet. I know we have 2 sheets of plywood @ $29
2 packs of skate bearings at $29 a pack
12' of pipe at an average of $3 per ft
tube ?
angle $10
hardware ?
acme thd rod ?
coupling?

So I am at $162 so far...

For the electronics, since I know nothing about electronics, I am going to suggest a 3 axis controller from xylotex for $145
http://www.xylotex.com/#3axis

3 steppers from ebay... figure about $100
http://cgi.ebay.com/SKC-NEMA-23-STEP...QQcmdZViewItem

A 24v power supply $39
http://www.web-tronics.com/dualout100wa1.html

A 24 v cooling fan $2.50
http://www.allelectronics.com/cgi-bi...209&type=store

So for the electronics I am at $287 so far.

Throw in a couple bucks for wire and connectors, and you're in business.

Your first project is to build a wooden enclosure for your electronics... I can't find the picture right now, but when I do I'll attach it here...

Mike...

well the steppers you mentioned are 6 wire and look like unipolar , the driver is a bipolar and the steppers are 3v ones so you would need large dropper resistors to correct the voltage ,(((edit yes they will drive them but the current looks over for that controler ))))


maybe you would be better using http://www.xylotex.com/3AxSysKit.htm

kit of steppers , driver , psu and fan

that way you know everything should be matched , rather than having to get bogged down in the maths needed to calculate the correct drive voltages for other steppers
, i got a stepperworld.com fet3 econamy system
well the steppers are under powered , the driver slow
anyway i modifyed the driver and got some bigger steppers , and built a psu for it , looks a bit of a mess but works http://www.whipy.demon.co.uk/cnc.jpg

going to have to redo the controls later and do away compleatly with the stepperworld driver

i am using 8 wire hybrid steppers that can be wired in eather bipolar or unipolar modes so it will leave the controler option more flexible
ac5711575225m from http://www.arceurotrade.co.uk/

Dave

p.s.
if using a wooden case for housing the electronics use a metal ( aluminium ) sheet EARTHED with the electronics mounted on that
and take usual care like unplugging before opening
most electronic component shops sell plastic project cases they are better suited
in my case im using a ip66 case as the machine is used outside so needs to be water tight

[mikeschn]

Hey Dave,

Your're right about the steppers. And that package deal that you found although a little bit more expensive, at least ensures that all the components match. :banana:

And I'm sure you're right about the enclosure too. Can anyone suggest an affordable enclosure for inside use?

Mike...