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limbo
11-25-2003, 04:45 AM
Just after completion of my first router someone told me that he had a large, old XY table lying in his garage. He gave it to me for free. It needs a lot of work but I couldnt resist: A second router had to be born. This is what it all started with:

limbo
11-25-2003, 05:13 AM
Cleaning and dissasembling yielded some great linear ball bearings (rexroth star) and steel guides. It took some guts to take the bearings off the guides because I was afraid the balls would fall out. I rolled up a clear plastic sheet to form a 3cm diameter tube and very carefully slid one of the bearings on it. It revealed I had nothing to worry about.

limbo
11-25-2003, 06:12 AM
I'm building something that will resemble the MAXNC router. I like the way the guides are below the table to keep the dust away and also the flat tabletop with open ends to allow for long workpieces. Construction is also fairly easy when you simply bolt the steel rods between the end-panels. This required some machining to drill and tap the head ends of the guides. Luckyly I found someone willing and able to do this. The first centimeter of the hole is widened to 12mm to accept a short piece of pipe that will also fit exactly in the end panel. If the 12mm holes in the panels are properly aligned this will be accurate enough to eliminate the use of alignment blocks.

limbo
11-25-2003, 07:03 AM
These are the MDF panels that build up the frame. Both identical panels were stacked and clamped together first and then drilled to ensure proper aligning of all holes. The holes for the shaft-bolts are slightly smaller than 12mm so this will give a nice press-fit for the short guiding pipes. (whats a good word for this?)

limbo
11-25-2003, 07:08 AM
Here are two assembled Y panels. On the rear one the small copper guiding pipes are visible.

limbo
11-25-2003, 07:17 AM
Below the original XY frame there was a small precision xy assembly hanging, of which I used one part to make the Z-axis. Travel is only 5cm but this is more than I need for routing plywood and balsa.

limbo
11-25-2003, 07:21 AM
complete Z axis. The Ferm tool is low quality and had to be modified. I took the front bearing out and wrapped it with electrical tape twice to make a tighter fit in the housing. This helped a lot. I also replaced the tool chuck with a better quality one. Much less runout and in total a better performing and quieter tool.

limbo
11-25-2003, 07:32 AM
YZ assembly. This is the last pic I have today. If y'all are bored to death or offended by this flood of naked router pics please stop me now!:p

regards,
John

Mr.Chips
11-25-2003, 08:51 AM
Limbo,
I can tell even though this is your 2nd machine you'r as excited as a first time builder. Lady luck has certainly smiled on you.
Your machine is looking very good, and I envy you of that highly polished work bench, it's first class.

Keep up the good work and please keep the pictures coming. It helps to stimulate us newbies.

Hager Hay

ToyMaker
11-25-2003, 08:57 AM
limbo:
keep 'em coming. I, for one, enjoy seeing what other folks are doing. It's wonderful brain-food.
You mentioned the z-axis is only ~2 inches (5 cm), and that you are only routing balsa and ply. What are you making? Are you doing any engraving?
Your y-axis appears to be about 25 cm (10 inches), how much x travel will you have?
robotic regards,

Tom
= = = = =
I'd rather have a free bottle in front of me than a pre-frontal lobotomy.

limbo
11-25-2003, 12:10 PM
I guess I can get somewhat overenthousiastic somethimes. Guys at work start throwing stuff at me when I talk about CNC:confused:. They were happy when the first one was finished. That highly polished workbench is our dining table.... Dont tell my wife :rolleyes: I already made a big scratch.
Toymaker, I'm making parts for R/C airplanes. Y-travel is some 18inch, X travel is 40 inch.

greetings,
John

balsaman
11-25-2003, 12:23 PM
Nice!

keep at it!

Eric

limbo
11-26-2003, 04:35 AM
A quick test of the X axis. This stacked drilling of the end panels really works! Theres no binding over the whole length. I had to wait a long time to get the shafts drilled and tapped so I made almost all other parts in the mean time. Would be a pity if they didnt fit or work as expected. Now everything is going together great and fast so I'm a happy camper :D. Next thing to do is cabling and cable guides on the Y axis to complete that unit.

limbo
12-16-2003, 04:43 AM
Finally found some time to finish the gantry and start on the total assembly. Frontside of gantry:

limbo
12-16-2003, 04:50 AM
And backside. Leadscrew pitch is 4mm and I'm getting 70IPM with the drivers from my old machine. They are 0.8A max while the steppers are rated at 1.4A. I'm planning to make new drivers that will (hopefully) increase the speed further.

limbo
12-16-2003, 04:59 AM
Complete frame assembled here. The gantry weighs around 30kg(guess) and that causes the X-rails to sag 0.5mm when the gantry is in the middle:mad:. I didn't expect that as the shafts are 3cm thick and MASSIVE! So now I've made adjustable support-bars for the tabletop to match the bend. Will post pics later.

Mr.Ed
12-16-2003, 05:21 AM
Hi Limbo, greetings from Ridderkerk,

You should consider yourself a bit fortunate to have gotten a donation like that.

Impressive construction, looks real sturdy.

I wonder what kind of electronics you're getting, i got mine from a German fellow, nc-step.de

My steppers ran only days ago for the first time, but due to circumstances i couldn't press on to start engraving or cutting something.

Good luck with the remainder of you project. It's looking good.

Mr.Ed.
(Edwin)

limbo
12-16-2003, 07:20 AM
Hi Ed, greetings to you too:p I'm in Weert, Limburg. Are we the only two Dutch guys around here? I've been following your progress too. Can't wait to see some pics of what you are doing.

My electronics are home made. They are based on the TCA3727 chips by siemens. Work really smooth but lack power. Now I'm playing with the allegro A3977, same chip as in the Xylotex driver. A bit rougher while running but lots more power. I think (hope) it will reach my 100IPM goal.

Cold Fusion
12-16-2003, 11:43 AM
Looks awesome dude!

Thank you sooo much for posting the pictures. They have been a big help for my cnc router that I'm starting to build.

limbo
12-18-2003, 04:59 AM
Here is a picture of my poor mans cat track. The idea comes from an old plotter, where a curved metal strip forces the cables to bend sharply. I reused the strip in my Y-axis cable guide. Then it hit me that this strip is similar to a normal tape measure. The flex tubing keeps tape and cables nicely together, and it turned out to work just as well as the original thing.

limbo
12-18-2003, 05:07 AM
btw,

Cold fusion, thanks for your nice comments. Hope you find some value in these pics. At least you won't make the same mistakes I made :D .

Greetings
John

cncadmin
12-18-2003, 10:37 AM
Very nice built and well thought out machine!

pack rat
12-19-2003, 12:23 PM
I really like clean and unobstracted lines. It cought me by supprise that is sagging by 0.5 mm. I have a similar shafting but thinner 25mm which means that it would sag more.I am curious to see your solution.

Cold Fusion
12-19-2003, 06:00 PM
I too would love to see how you made your rod supports. Any other pictures you might have would be great too.

limbo
12-22-2003, 06:14 AM
One solution that came up is to mount the whole machine on top of two sturdy H-bars, placed below the X- rods. Then the gantry could have some cams that serve as "wheels" to ride on the H bars. This would take the gravity force off the X- rods. However, for me its difficult to find H bars or something thats sturdyer than my X-rods. As I only cut parts for model airplanes I can live with the sagging as long as my tabletop sags in the same manner, keeping the depth of cut constant. The tabletop itself is made of MDF that needs two bars for supporting it. I made these from cheap levels and found a way to adjust the stiffness by tightening a screw. Difficult to explain but the following pic will explain it (I think):p .

Greetings,
John

limbo
12-22-2003, 04:47 PM
Another update..

This is the finished machine shown topless. I bumped into these levels at 3.99 euro a piece. Thats even cheaper than bare aluminium profile.. (at least where I can get it):D. The adjusting screw in the middle isn't really visible in this pic.

limbo
12-22-2003, 04:55 PM
Closeup of the drive nuts and cable guide. The tubes on both sides of the nut limit the side to side movement of the leadscrew. This helped to lower the backlash and also reduced whipping at high speeds. The nut is an antibacklash idea found on this site. When I dial out the backlash competely it will cost me some speed, so now I have something like 0.05mm. Good enough for my balsa parts.... Speed is now 80 IPM on X and Y.

limbo
12-22-2003, 04:58 PM
ready to go

limbo
12-22-2003, 05:08 PM
Since I'm so busy polluting otherwise fine bandwith here: A piccy of my firstborn.

Greetings,
John

balsaman
12-22-2003, 06:20 PM
Nice Job!

Eric

limbo
12-23-2003, 04:19 PM
Balsaman,
thanks, I read your thread dozens of times. Your machine and the others on this site are great inspiration!
I didnt use the old one very often because it was too slow at rapids to be practical. This one has coarser pitch screws so it rapids fast, but at lower torgue. I hope the actual cutting can be faster than before. So far I tried only 3mm plywood at 400mm/min (16IPM) in one cut with a 2mm bit. About the same as what I used to do on my old machine. Its too late to experiment more today. I wonder what speeds I should expect with a dremel clone? Would changing to for instance the 900W kress router help, in a way that cutting forces decrease so that the speed can be increased?

Merry Christmas to you all!
John

Cold Fusion
12-23-2003, 05:48 PM
Have you tried cutting any metals with it?

Erkan
12-24-2003, 08:29 AM
Hi Limbo,

Your CNC machine is looking good. I'm making a CNC router. Mechanical side of the CNC is finished.

I have a question for you. What size stepper motor did you use your CNC machine. I going to buy a 300 Oz-inch Nema 34 size stepper motor.

How can I examine motor torque. Could you tell me some information about this issue.

My CNC Dimension : Y:30" X:23" Z:5"
Router : Boch poh 500A 30000 Rpm


Thanks

limbo
12-24-2003, 05:09 PM
cold fusion,
I've read somewhere that dremels aren't really suited to cut metal. They would flex to much, causing the bit to clatter. I haven't tried it. Maybe its possible in several light cuts.

Erkan,
My steppers are 24 size, 3.5V/1.4A. I think I saw 60Ncm in a datasheet but I'm not really sure. Now I run them at only 800mA so it seems that you don't need much thrust to cut plywood. I tried the same part today at 30IPM. No problem. Then I tried setting the acceleration in turbocnc very low and just let it rapid into the ply to see where it stalls. I didn't ! :D Thats amazing because above 60-70IPM theres very little pushing force left. At 30IPM it delivers only a few kilos, measured simply by having the gantry run into a scale (a spring type), placed on its side.
I'm real curious to see what the others get here... Anyone tried this? How much thrust is really necessary to cut 1/8 ply with for instance a 1/8 bit at a given feedrate? How fast do you guys cut 1/8 inch plywood in a single pass?

all the best,
John

balsaman
12-24-2003, 05:25 PM
I accidentally cut 3/8" hard maple with a 1/8" bit at 150" per minute in one pass. It didn't break the bit.

Eric