Hi, I’m thinking about designing and building a custom machine to drill rectangle steel tubing. The tubes vary in length from about 48” to 90”, and are 3x6, 4x6, and 6x8 tubing sizes.
The tubes all have 2 sets of three 7/16 holes, in a straight line, with 2” spacing between them.
I have already designed a 3 spindle head, using purchased straight shank ER25 collet holders that I will turn for bearing journals, etc. The trick is to use one motor, to drive all the spindles. The plan is to use 1/2” wide L or MXL timing belts to transmit power to the remaining spindles. I’m going to speak with an engineer from a manufacturer of timing belts to find the torque rating. But it seems to me it should be sufficient. Then the motor HP. I found an online drill horsepower calculator, and unless I missed something, a 3hp 3ph motor at 1725RPM should be adequate to drive all three spindles with 7/16 drills. The plan is to run the spindles around 500-750 rpm. I could do this with a fixed rpm by changing the pulley sizes, or possibly drive each motor with a VFD.
I did quote a drill head from Zagar, and their price was a little north of 14k. I really need 4 drill heads to accomplish what I need. So their price would probably drop if buying 4 units, instead of one. Either way, I still feel the price is far too high.
Basically, do you feel that timing belts to transmit power from one spindle to an adjacent spindle is a bad idea, and is a 3hp motor to drive all three spindles at one sufficient? Or too much hp?
Thanks!
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The tubes all have 2 sets of three 7/16 holes, in a straight line, with 2” spacing between them.
I have already designed a 3 spindle head, using purchased straight shank ER25 collet holders that I will turn for bearing journals, etc. The trick is to use one motor, to drive all the spindles. The plan is to use 1/2” wide L or MXL timing belts to transmit power to the remaining spindles. I’m going to speak with an engineer from a manufacturer of timing belts to find the torque rating. But it seems to me it should be sufficient. Then the motor HP. I found an online drill horsepower calculator, and unless I missed something, a 3hp 3ph motor at 1725RPM should be adequate to drive all three spindles with 7/16 drills. The plan is to run the spindles around 500-750 rpm. I could do this with a fixed rpm by changing the pulley sizes, or possibly drive each motor with a VFD.
I did quote a drill head from Zagar, and their price was a little north of 14k. I really need 4 drill heads to accomplish what I need. So their price would probably drop if buying 4 units, instead of one. Either way, I still feel the price is far too high.
Basically, do you feel that timing belts to transmit power from one spindle to an adjacent spindle is a bad idea, and is a 3hp motor to drive all three spindles at one sufficient? Or too much hp?
Thanks!
Sent from my iPhone using Tapatalk
