2nd Build - Steel Tube, Moving Gantry Style, Mill / Router

**amishx64** · 05-29-2010, 11:57 AM

WOW. This is really looking good so far. Can't wait to see the rest.

**InventIt** · 06-29-2010, 08:57 PM

Made some more progress. I got the base and y axis bearing mounts back from the machine shop.

Even though the machine work was ALOT more then I expected to pay, I really think it was worth it. I expect to have a machine that cuts square and has much more precision then the first design. Having all the bearing mounts trued up on a machine that's holds tolerance withing 5 microns gives me a sense of reassurance that i should be able to hold good tolerance on this machine.

Welded up a stand, primed, painted and mounted the base.

I chose silver grey because it was leftover from another project so it was a freebie.

Hope to get some time tomorrow to set the y axis.

I know it's a long way off but I can't wait to see this thing move!!!

**InventIt** · 07-04-2010, 12:23 AM

Some more progress....

tonight I finished drilling and tapping some misc. holes in the 46" long carriers that support the y axis. Then I sprayed Boesheid T9 on all the bare metal machined surfaces and mounted the carriers to the towers. There are four 3/8" bolts that are accessible from inside the towers that hold the y axis carriers to the top of the towers.

Also got the the Rexroth 25 linear bearings for the y axis cut to length and mounted them to the carriers.

I intentionally had the slot cut into the carriers so I could use these toe clamps to wedge the rail against the reference edge as I tightened the mounting bolts.

**InventIt** · 08-22-2010, 10:33 PM

Well, it's been a while but I finally got some more work done on the mill. I had been thinking of using ball screws instead of the acme thread and delrin nut, but the cost was too high. So I used what I had. After the machine is running and depending how good or bad the acme and delrin holds up I'll consider changing it over to ball screws. Should be easy to do.

Anyway, here it is...

Very similar to my first router. Machined the end mounts that hold the bearings, machined the screw ends and mounted them into 1" shafting stubs that fit into the bearings. These bearings are deep groove type and although very inexpensive, they have almost no play. In the double configuration with light preload between them there is less then .001 backlash. Also the flange type bearings allow easy alignment of the screw in relation to the linear bearing. The screws turn silky smooth.

Next step is to set the gantry onto the y axis platforms and mark the bolt holes. Then I can mount the gantry and start working on the x axis. Also need to make a beam that spans the y axis rails and mount the pulleys and motor. Lot's to do!

**InventIt** · 08-25-2010, 10:42 PM

It's starting to look like something.

While i'm still waiting for the pulleys to connect the two y axis screws to the servo, I got the gantry set up onto the y axis rails and mounted the x axis linear bearings. Everything is fitting together really well. Having all the critical parts machined is making assembly really easy. I should get the pulleys and timing belts this week from SDP-SI so I can get the y axis finished.

Getting itchy to see this thing move under cnc control!

**InventIt** · 09-23-2010, 09:23 PM

OK, finaly got the y axis drive done. Machined the 44t Gt2 5M pulleys from pulley stock I got from Sdpi. Used Fener Drives tapered bushings for attaching the pulleys to the screws. I made the pulleys 1" wide in case I needed to upgrade the 15mm belts that are now in the machine. Turns out that 1100w servo motor can really stretch those belts and i will have to get the wider belts.

I may make flanges for the screw pulleys, can't imagine the damage that would happen if one of the belts came off in the middle of a G00 move at 600IPM!!

video of the y axis doing some moves.
[nomedia="http://www.youtube.com/watch?v=OORg43YlVoE"]YouTube - CNC Machine first test Y axis[/nomedia]

**berzer** · 09-28-2010, 04:00 AM

Very goood looking machine

Can you estimate the cost of it?

**InventIt** · 09-29-2010, 07:47 PM

Originally Posted by berzer

Very goood looking machine

Can you estimate the cost of it?

Well, i haven't really been keeping track of it. Some of the costs as as I remember:

Steel tubing and plate cut and bent as speced $800
Servo drives from ebay $1200
Machine work was about $2000
Misc parts $1000 ??
So about $5000 so far.

The first router I built cost me about $3500 and it's no where near as nice as this one. So I guess 5k isn't too bad.

**InventIt** · 11-10-2010, 09:58 PM

Work on the router has been slow going because I had a little hitch in my plans for the Z axis. I original was going to use the Z axis assembly from my first router but realized it was too short to work on the 2nd router which has more height under the gantry. Also the old z axis is only 3/4" x 6" alum and most likely would not be stiff enough. So I decided to make a new z axis assembly out of 1" x 8" cold roll 1018 steel. However when I took my 3 plates to the same machine shop that did the machine work on the base and gantry, I got sticker shock! Almost 2k to rough 3 plates and drill/tap a few holes!!!! Ouch!
So, I figured it was time to look for a old manual mill. A few weeks later I had 5000# of good old American iron sittin in the shop. Sweet!

**InventIt** · 11-10-2010, 10:27 PM

Ok, now that I have a mill, I can get some work done.

The X axis bearing blocks, motor mount and delrin nut are done. 1100W servo with zero backlash coupler.

During tuning of the X axis servo the motor went into oscillation and before I could stop it it broke the coupler. Then I got the 3 piece coupler that is on it now and it went into oscillation again and before I could get it shut down it destroyed the red plastic spider. I was amazed how much power these servo motors have to be able to do that. So, before any further tuning i setup a E-Stop. Finally I managed to get the X axis tuned.