Apparently the Mantis can be made for less than 100 bucks not including the controllers and steppers and such. I think this is a great project because it can do all sorts of cool stuff like cutting PCB circuit boards, cutting plastics and wood. What a great platform for learning about CAD, CAM, CNC and such. Not to mention going to town cutting things.
For steppers and control I have a 30V 5A power supply I picked up on the cheap on ebay (used). Also, I managed to find some nice Nema 23 stepper motors from an Ottawa Robotics member. The same member also sold me three controllers. The wiring came from the generosity of Guy of Ottawa Robotics. This configuration might be overkill for the project but I was already building a CNC mill so I have this stuff on hand. (The 4-axis controller you see in the background of the stepper detail is the controller for my CNC laser cutter).
I’m thinking of extending one of the axis of the machine. That might be interesting for cutting larger wood and platic parts.
Here is the BOM for one supplier McMaster-Carr according to Leigh who is championing this project:
1 Machine: $170.74 2 Machines: $221.17 [$110.59 ea] 3 Machines: $271.60 [$90.53 ea] 4 Machines: $322.03 [$80.51 ea] 5 Machines: $372.46 [$74.49 ea]
The incremental cost per machine is $50.43, for any number from 2-5
Here is a breakdown of the BOM For the shared, and unshared portions
Unshared parts: Part# Description Qty Price Ext 60355K503 R4 .25" ID .625" OD bearing 2 4.71 9.42 2868T17 .625x.75x1" bronze bushing 1 0.93 0.93 9414T6 .25" shaft collar 1 0.58 0.58 6061K108 .375x10" precision rod 4 4.86 19.44 6061K422 .375x7" precision rod 2 4.17 8.34 2868T72 .375x.5x.625" 863 bronze bushings 12 0.56 6.72 98935A817 3/8-12 lead screw 36" 2G 1 5.00 5.00 ---- 50.43 Shared Parts: [for up to 5 units] Part# Description Qty Price Ext 5234K72 Nylon/silicone tubing - 1ft 1 1.01 1.01 94639A189 .09x.25x.3125" spacer [100pcs] 1/100 7.99 7.99 1817T13 5/8 O.D.-1/4 I.D. Delrin AF tubing - 1ft 1 14.60 14.60 90283A112 4-40x.625" flat pan head screws [100pcs] 8/100 1.56 1.56 92949A199 8-32x1" screws allen button head [100pcs] 7/100 8.05 8.05 90975A012 8-32 tee nuts [100pcs] 7/100 6.74 6.74 90126A512 8-32 washer [100pcs] 7/100 1.29 1.29 90252A104 #6x.75" plywood screw phillips [100pcs] 17/100 6.66 6.66 25345A42 ACME 3/8-12 Tap 1 72.41 72.41 ---- 120.31
Whups… I forgot, there is an error in my BOM. The R4 bearing is incorrect. The bearings are supposed to be shielded. The proper part should be: 60355K43 [replaces 60355K503] They are only slightly more at $5.10 ea from the 4.71 ea in the BOM.
Tom Burns (Dec 6) of Ottawa found a nice independent build log at http://trackhacker.com/archives/430
There is a much better BOM: bom-9
Tom Burns (Dec 8th) sent this link: http://crevicereamer.com/Page_2.html
Project Update: I think the Mantis project isn’t really attractive enough for people to get over the time it takes to make it. The Toronto group didn’t actually do the bulk order for parts that they talked about. The Ottawa group isn’t really hot on it either. I decided to just do this on my own but not follow the Mantis plans. Instead, I’ll go to a slightly larger cutting area and a few other improvements. I’ve already ordered a pair of Nema 17, 3-axes systems with motors. They came without power supplies but I’ve already bought a supply for one of them. I’m still shopping for the second supply. I’m now working on some ideas for the linear bearings. I ordered 150 bearings from VXB to try some of the ideas I use on my laser cutter. I have a telephone meeting with a linear bearing sales person on Wednesday. They have some plastic bearings. I will consider that. I think I’ll publish the plans and have pinged around for a name for the project. Any ideas? Feb 6, 2011