Messages

31

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: August 25, 2010, 11:46:09 PM »

Well, after hearing the price for the ball screws I decided to use the acme screws for now, at least on the y axis. Maybe in the future I'll upgrade the screws if the need arises. Would have been really sweet with zero backlash ball screws on this machine.

Got the y axis screws mounted. Used the inexpensive stamped steel flanged bearings. They actually work very well. There is less then .001 backlash in the whole system.

Also got the gantry set onto the y axis platforms and mounted the x axis linear bearings. Used the same toe clamps to hold the rail against the reference edge, same as on the y axis bearings.

32

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 24, 2010, 07:43:50 AM »

Can anyone help me with ID'ing this spindle and it's components?


I bought this spindle cartridge off ebay a while ago. Plan is to use it on this router when it's done. It was expensive and I don't want to destroy it. So, not knowing anything about it can anyone help me by pointing out anything I should know?

I was told it is from a Kitamura Mycenter 0. Supposed to be a 15000 rpm unit, and has a bt30 taper. This seems to check out looking at the specs on the Kity site. A Mycenter 0 has a BT30 taper and can come with an optional 15000 rpm spindle. OK, so maybe this is true.

The questions I have about it:
I think it is it an air/oil feed lube type spindle? Is that what the hole in the mounting flange is for (with the red plug)? If it is an air/oil feed lube type, how much air pressure, how much oil, how ofter and what oil do I use? What is the hole in the side, near the center, that has a hex plug in it for? What is the notch in the aluminum part at the top where the draw bar pokes out used for if anything, maybe alignment during a tool change? Can I apply force to the draw bar and have that force held back by the bearings or is the flange under the aluminum part used for squeezing the draw bar between the part that sticks out and the flange therefore not putting excessive force on the bearings?

Lot of questions... Any help would be appreciated. Thanks

33

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 22, 2010, 10:14:59 PM »

Regarding Ball Screws...

If I do go with ball screws, what would be a good lead to choose? Nook has .200, .250 or .500 leads

I used .500 lead on the last router, and I was planning to use .500 lead acme screws on this. Judging from recent experience, maybe a finer resolution would be better though. I have more then enough RPM from the servos for the finer pitch screws, the limiting factor is whip from the x axis screw.

just thinking... If I went with .200 lead or 5 turns per inch I could possibly see 400IPM If I can get the longest (67") screw up to 2000 rpm?

According to Nooks critical speed calculator, I can get about 1900 RPM from a 1.15" screw, however, the ends need to be supported with angular contact bearings spread apart a minimum of 1.5x dia of the screw and at both ends. With regular ball bearings at both ends the RPM limit drops to 1266 or 253IPM.

So, are the calculations Nook uses conservative? Can I massage the numbers a little and still be OK?

My original goal was 600IPM, but 400IPM would be OK. Less then 400 may be a problem though.

What are your experiences?

Thanks

www.nookindustries.com/engineering/calculators/CriticalSpeed.cfm

34

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 21, 2010, 10:56:43 PM »

I am at a juncture in this build where i have to decide if I want to spend the extra money and get ball screws or continue on the path I was originally going and stay with acme screws and Delrin nuts. I am guessing the ball screws will last longer and have no backlash. Also the ball screw I was looking at are accurate to +/- .001 (Nook XPR) whereas the Acme screw is only good to +/- .009 per foot.

I used the acme screws and Delrin nut concept on the first build and it has been ok. I noticed recently that the Delrin nuts are starting to get some backlash on them. They had been tight without backlash until recently.

Anyone want to chime in on this?

35

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 21, 2010, 10:38:23 PM »

Got a little more done  

In an earlier post I showed the 16x24" electrical box as it was when I bought it. Since then I cut out the back and left side and mounted a 1/4" thick aluminium plate to the back of the box. This allowed me to drill and tap the mounting holes for the drives and other electrical gadgets. Mounted some large heat sinks (3) to the back of the aluminium plate for cooling. Plan to make a operator panel for the left side.

From left to right, there are 3 Danaher drives for x, y, z. Then a 1kw A/D servo drive for the spindle. Then another Danaher drive for 4th axis. Galil ICM2900 mounted to far right. There is a opening for the 100 pin cable connection at the right side of the box. Power will come into the box from the bottom and I have distribution blocks I can mount to the din rail under the drives. I am going to take an approach similar to how the machines at work are laid out to help fight EMF. Basically, the high voltage ac devices are mounted in a separate chassis and include ac circuit breakers, transformers, high voltage relays etc. Another chassis will house the servo drives, I/O and other noise susceptible devices.

Also started mounting the y axis limit switches and trips.

36

General Mach Discussion / question about spindle control

« on: July 08, 2010, 09:16:55 AM »

I have a Galil card I will be using for the mill I am building. The Galil card can handle 5 axis, however I don't want to have to run another 100pin cable from the computer to the mill and add an additional  i/o board just for one axis. So I would like to stick with only 4 axis's total.


So, with only 4 axis's available, I need three for x, y and z and I want to be able to do tapping (with a tension/compression tap holder) and also have a 4th rotary axis for parts I have a commitment to make for my job.

So, my question is, can Mach control the spindle speed and direction without it being an axis or would it just be wise to get the extra cable and i/o board and use the 5th axis in the Gaili card for spindle control?

Thanks

37

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 04, 2010, 12:19:05 AM »

i guess the next thing will be mounting the gantry and making end blocks for the lead screws. That will most likely take some time to get done.

38

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: July 04, 2010, 12:06:50 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.

39

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: June 29, 2010, 08:37:54 PM »

pic

40

Show"N"Tell ( Your Machines) / Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router

« on: June 29, 2010, 08:37:07 PM »

Got a coat of silver gray on the base and mounted it to the stand. I chose that color because it was leftover from another project so it was a freebie.

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