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Author Topic: 2nd Build - Steel Tube, Gantry Style, Mill / Router  (Read 22739 times)

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Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #30 on: July 04, 2010, 04:29:22 PM »
Looking good!

Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #31 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.
Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #32 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????

Offline Sam

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Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #33 on: July 21, 2010, 11:15:02 PM »
well.....I mean....considering the investment (time and money) that you have already put forth in this project, I would go for the ball screws. If it were me, the delrin and acme screws wouldn't have even entered my mind. Great job so far, by the way. Keep the pics coming!
"CONFIDENCE: it's the feeling you experience before you fully understand the situation."
Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #34 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?



Offline RICH

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Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #35 on: July 23, 2010, 12:02:48 AM »
Attached is Nooks formula for determining critical speed. Didn't try the calculator......
You can also take a look at other manufactures guidelines. Are they being conservative, well, sometimes companies have deternined
what is good engineering practice based on time tested information. If you want to ignore the info,  then sound engineering experience
or analysis would enter into the judgement. What you want is to operate away from the critical speed
and other possible harmonics. Naturaly this is not limited to just the simple calculation as other things can come into play.

Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #36 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
Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #37 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.

Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #38 on: August 25, 2010, 11:54:03 PM »
Couple more pics...
Re: 2nd Build - Steel Tube, Gantry Style, Mill / Router
« Reply #39 on: September 23, 2010, 08:08:23 PM »
Worked on finishing the Y axis drive. After running the axis a few times, I think it needs larger belts. Sdpi didn't have the 25mm belts in stock, so I got the 15mm wide belts. I made the pulleys wide enough for a 1" belt. I machined the pulleys from pulley stock. The gadget you see holding the pulley on the shaft is a tapered hub. Fener Drives supplied those, very nice.

I do need to change that upper idler pulley so it has grooves in it for the teeth on the belt. I can't believe how much noise the belt makes going over that flat idler.

Quick video of me testing the Y axis drive.