100 Watt CNC Laser Installation

The new motors are so large that they dont fit the nema 34 sized system on my table. I sent in a fax:

to a Rockville operation called Halpro and they made two parts in less than 2 hours for $125. Pretty nice experience.

Called 'em spoke to Helen Chan. She said it wont ship for 4 weeks. Arg. They make the part custom and they're fully booked. Nice cheap price though ~$120.

Dear Sir or Madam:
Enclosed are laser parts that I recently obtained second hand to serve as the optics delivery for a Coherent G100 CO2 laser. I am in the process of building a CNC table for cutting and marking steel. I have contacted Gilbert over the phone and email a couple times and he suggested that I ship these parts to request a quote for fabrication of two adaptors. One adaptor will connect between the extension tube and my collimator, the second between the collimator and cutting head. I will be running nitrogen in the optics system between the laser head and the collimator, and I would like a price quote for modification to place a gas port on the extension tube. Please, this is just a home project with a limited budget so assist me in reducing costs anywhere it is possible!

The parts I have shipped to you are the following:
1) Beam polarizer and elbow combination
2) 12 inch extension tube with bellows
3) Collimator/beam expander
4) Haas cutting head

I am aware that the optics should be sealed more appropriately from dust and debris. However, this is how they were shipped to me so I’m afraid there’s not much I can do to improve their current condition.

I look forward to hearing from you and would welcome any additional comments you may have concerning my project. Please contact me by email or my work phone.
Sincerely,
-me

I ordered some stuff for the power supply from Digi-key

Quantity Part Number Description Price
-----------------------------------------------
1 432-1067-ND CIRCUIT BREAKER THERMAL 10A $2.02
1 432-1068-ND CIRCUIT BREAKER THERMAL 12A $1.66
1 294-1088-ND HEATSINK PWR .90"H BLACK TO-3 $3.69
2 WM5790-ND CONN BARRIER STRIP 2POS .438" $3.22
3 WM5763-ND CONN BARRIER STRIP 6POS .375" $9.87
1 C2105B-100-ND HOOK-UP WIRE 14AWG STRND BLK $21.41
100 A1073-ND CONN SPADE 14-16 AWG #6 PIDG $19.49
100 7622K-ND CLAMP CABLE .187/.140 NYLON $4.21
100 7629K-ND CLAMP CABLE .375/2.03 NYLON $4.64
1 Q116-ND CORD 16AWG 3COND M/F BLK 118"SJT $4.88
1 360-1185-ND SWITCH PWR TOGGLE SPST 15A 5PCS $5.28

cheap too:

www.mcmaster.com


This may be useful as a support that goes between the table and the parts that are getting lased.

I bought der motors on ebay. $225. Here're the specs:

37.51 Oz-In/A
25.0-30.5 V/KRpm
Motor Terminal Resistance .75-1.02 Ohms @ 4A.
Maximum Terminal Voltage 60V
Maximum Continuous Speed 2100 RPM (No Load)
Maximum Peak Torque 1500 Oz-In.
Maximum Peak Current 44.5A
Maximum Continuous Stall Torque At Max Motor Temp 300 Oz-In.
Maximum Continuous Current 8.9A

There are piles of posts of this on yahoo: CAD_CAM_EDM_DRO.


http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/message/64121
http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/message/65201
http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/message/66995


Since I have a target voltage I can go about buying the toroidal transformer.

If you look at the sketch1 there's a cnc table that'll carry the part underneath the beam. This is the table.

This will require building a fairly large power supply to drive the table's servos.

I encountered some documentation (here and here ) which desribes the formulary in order to build a power supply for servo motor drivers. Using the assumption that the servo will require around 68 VDC to operation @ 10A, the theoretical amperage requirement is 2 * 10 * 67% = 13.4A.

The manufacture Plitron sells toroidal transformers. They have some useful technical notes. To calulate the desired transformer voltage I used the formula: (68VDC/ 1.4) = 48.6 VAC. Plitron uses a slightly different formula which is (68VDC + 2) * 0.8 = 56 VAC. At this voltage it looks like I need a 13.4A * 55VAC = 743 VA rated toroid transformer. I think because I could possibly use more amps the transformer I'm considering purchasing: 117042201, two 55v secondaries @ 9A each, $139.73. See plitron's toroidal ratings.

At this amperage and using the formula ((80000 * I) / V) I estimate I'll need around ((80000 * 18) / 68) = 21167 uF filter capacitor. I purchased five Model#: 3VTLM153M80V, 15000uF, 80V electrolytic caps on ebay and I'll wire two in parallel. I also purchased 4, 25 Amp 200 Volt bridge rectifiers,$4 each.

I made a spread sheet that helps perform these calculations.