Newbie- Need help designing 2' x 6' router for ski/snowboard construction

[Rswilliams13]

Hey guys,

I am new to CNC routers, but I have been doing a lot of research lately, and received a lot of great info from this site. I just finished up school, and I am starting a small custom ski and snowboard manufacturing company based in Lake Tahoe. I just received some initial R&D funding to create my CNC router, pneumatic press and produce some prototypes. I have taken autocad and solidworks classes, and am looking to build a high quality cnc router to produce the parts I have designed.

The primary use for this router will be cutting out the outline of ski/boards and creating the thickness profile of my wood/bamboo cores as well as some UHMW plastic pieces that are used for the sidewall/tip/tail construction. However, I would like to make the machine as versatile as possible, and will be using it to create more CNC routers and parts in the future. I would like it to be able to machine aluminum, and will probably fabricate a plasma cutter attachment for it at some point down the line.

I am looking to build the machine with a cutting area of approximately (slightly more than) 2' x 6'. I have a budget for the build of approximately $2000 for the machine and electronics (I already have a windows xp computer with parallel port, autocad, solidworks, bobcad/cam and Mach3). I have a full shop at my disposal and am an accomplished MIG welder. I am on a bit of a time crunch and need to have a working machine within 2 months. Here’s a basic overview of my plans so far:

Spindle: Bosch 1617EVS 2.25hp variable speed router

Z AXIS: K2 CNC's 5" travel z axis assembly and 3.5" router mount:
K2 CNC Router 5" Linear Slide Actuator - ZA500QR Z Axis- Nema 23/34 motor mount | eBay

GANTRY & TABLE: I will either be fabricating the gantry out of 2" square steel tubing or possibly 3060 extrusion w/cncrouterparts.com gantry risers. My plan for the table is to fabricate the table frame from 3" tubular steel with a 2.5' x 7' opening to allow an 8" thick 2.5' x 7' MDF torsion box to be mounted as a work surface/surface to mount my jigs. The gantry will mount to the steel frame and allow the torsion box to be removed.

X AND Y AXIS DRIVE SYSTEM: I am planning on purchasing three of cncrouterparts.com's NEMA 23 3:1 belt reduction Rack and Pinion drive systems. Two for the x axis, and the other for the y axis. link here: CNCRouterParts

I will be ordering (2) 7' 20 pitch racks for the x axis, and one 3' 20pitch rack for the Y axis from Moore Gear. The x axis racks will be mounted to underside of the steel tubular table frame I am fabricating.

Please let me know if I am on the right track so far and if you have any other suggestions. I am looking at these prefabricated parts partially due to my timeframe for completion, and they seem to be well designed and offered at a fair price. I am more than open to other suggestions though.

QUESTIONS

Electronics?: I have been looking at the NEMA 23 setups available, and it seems most places offer essentially the same kits at roughly the same price. I will be needing 4 stepper motors for my current design, 2 for the X axis, and 1 each for Y and Z. What TQ steppers do you recommend for my setup? I figured the 425oz/in NEMA 23's would be fine. Can i get away with the lower power 287OZ/IN steppers availible? Seems like the best price i can find for a 4 axis 425oz/in kit is about $500, and the 287's are about half that.

Linear Motion? I have been debating back and forth numerous times on what to use for linear bearing rails. The Z axis is taken care of, so I just need to answer the X and Y dilemma. For the X axis I am thinking of using the extended carriages from cncrouterparts that run on 1/4" cold rolled steel. I may also use them for the x axis, but am undecided. please let me know if you have any thoughts or suggestions.

Thanks guys, I am exited to get started on the build. I would greatly appreciate and advise you guys can give!

-Ryan

[PaulRowntree]

Hi Ryan, welcome to the Zone!
It sounds like a neat business plan. I am not using my machine for business, so others would have better feel about some of the information you gave. I was just wondering ..
1) Why 2'x6'? If you made it a bit wider (3'-4'?) you would have much greater throughput for not much more cost. Plus it would put your Y-R&P to better use. If business is good, you don't want to have to rebuild for greater capacity.
2) Why mount a wood torsion box to steel frame? It would decrease your stability (MDF vs steel) and possibly forces your gantry to be higher than it needs to be (depending on where your X rails are relative to the table top). You need a sheet of something as a mounting surface, but I don't see the point of the box.
3) If your pieces are pretty similar sizes, vacuum pods may be a better alternative to spoil boards and clamping jigs.
Good luck!

[JerryBurks]

Others will chime in on the technical details (looks to me like a good overall plan). But, being in a build myself I think the 2 months are really aggressive, considering shipping times and the actual work to cut and assemble (not to mention measure, check, measure and check again).

But, if you are ready to work 15-hour days I guess it can be done (assuming you have some detail design already).

[Rswilliams13]

Originally Posted by PaulRowntree Hi Ryan, welcome to the Zone! It sounds like a neat business plan. I am not using my machine for business, so others would have better feel about some of the information you gave. I was just wondering .. 1) Why 2'x6'? If you made it a bit wider (3'-4'?) you would have much greater throughput for not much more cost. Plus it would put your Y-R&P to better use. If business is good, you don't want to have to rebuild for greater capacity. 2) Why mount a wood torsion box to steel frame? It would decrease your stability (MDF vs steel) and possibly forces your gantry to be higher than it needs to be (depending on where your X rails are relative to the table top). You need a sheet of something as a mounting surface, but I don't see the point of the box. 3) If your pieces are pretty similar sizes, vacuum pods may be a better alternative to spoil boards and clamping jigs. Good luck!

Thanks for your input and warm welcome!

The reason I am looking to keep it smaller is primarily space constraint. I am not actually going to launch the business for a couple years, but will be using this router to get my CAD designs fine tuned and produce small quantities of boards for R&D. Until launch, I only have a 1.5 car garage to work with at the house I am renting and will need room for my table saw, thickness planer, large pneumatic snowboard press, ect. Once I feel ready for launch, I will be building a couple more cnc routers that will actually be my production machines. I figure making this one will help me figure out what exactly I need and ways I can optimize the final production machines. I am looking to make the machine footprint 7' x 3' with a cutting area slightly larger than 2' x 6'. The boards I am making will be no more than 14" wide and 5.5' long, ski's will be up to 6'2"

Good point on the box. I was thinking a torsion box would be more stable. Now that I think about it, I would not have it bolted to the steel frame, but rest inside it with an overhanging lip. Definitely open to suggestions here. Do you think a simple steel ladder frame base with MDF on top would suffice?

I have been mulling over a vacuum setup. However I will be producing varying shapes/sizes of boards and also ski's. For now I am going to make clamping jigs, but figure I can play with vacuum systems down the line.

Thanks again for the ideas!

[Rswilliams13]

Originally Posted by JerryBurks Others will chime in on the technical details (looks to me like a good overall plan). But, being in a build myself I think the 2 months are really aggressive, considering shipping times and the actual work to cut and assemble (not to mention measure, check, measure and check again). But, if you are ready to work 15-hour days I guess it can be done (assuming you have some detail design already).

haha, yeah I know it's a very aggressive timeline. The reason behind the crunch is a good friend of mine spilled the beans on my business plan to a very wealthy potential investor who called me up and wants to fly me out in february to go over my business plan. My goal is to produce a finished product by then, and the router is only one piece of the equation. I took 6 weeks off of work starting Nov 1st, and am planning on building the router then. My goal is to finalize the design and get all the parts I need on order within a week or two so that come Nov. 1st everything is waiting for me in the shop. Fortunately I have the use of a complete shop and the help of my father and a few of his retired buddies who are great craftsmen to lend a hand. Not to mention some good friends of mine who'll work for beer

Thanks for the encouragement and good luck on your build. I'll stall a build thread when I get underway - Ryan

[Rswilliams13]

So do you guys think the 425oz/in NEMA 23's are my best bet? Can I get away with lower TQ rating? Any advice is appreciated!

[ger21]

Originally Posted by Rswilliams13 So do you guys think the 425oz/in NEMA 23's are my best bet? Can I get away with lower TQ rating? Any advice is appreciated!

It depends on the drives you use.
The most popular combination with that r&p setup is the Gecko G540 with 381oz motors. They'll outperform the 425's with the G540 due to their lower inductance.

[PaulRowntree]

What I know about planning & running a business is ... zip. But if you are using this machine to do prototypes, you want to make it at least as solid as your final production hardware. I think a steel frame is a good idea, 3x3 seems strong if the supports are frequent enough, but then I would connect side to side with 2x2 tubes and use this as the support for your bed.

Get a feel for the deflections for supported steel beams, and compare this to your requirements. I use the botlanta calculators, but I know there are others

Beam Deflection Calculator

A 16" long cantilever (diving board) of 3x3x0.25 will deflect ~0.001" with 100 lbs of force. So supporting this tube every 30-36" should keep the X rails straight. Diagonal brace it to avoid racking. If you are good at MIG, then it should be cut, fit and go. Most folks mount the tracking on top of the X supports just to make the gantry sides shorter. If on top then the supports to the Y rail are vertical, less side-to-side forces to consider.
Check out CarveOne's steel-frame builds. There are lots of details given. And for a truly over-the-top steel build, google MadVac. Again, lots of good thinking there; even if you don't emulate it 100%, it is good to see the thinking elaborated.
Cheers!

[JerryBurks]

Originally Posted by Rswilliams13 haha, yeah I know it's a very aggressive timeline. The reason behind the crunch is a good friend of mine spilled the beans on my business plan to a very wealthy potential investor who called me up and wants to fly me out in february to go over my business plan....

Ryan,

a good business plan always has a contingency section. I would look around for CNC owners with larger machines in accessible distance so that you can deliver the product sample anyway, no matter if you run into the inevitable problem with the machine build. Keep in mind you want to make money building boards and the CNC while a fun thing to do is just means to that end.

It would suck to fail just because somebody ships the wrong parts, you drill the wrong place or the software won't run on your machine.

JB

[Rswilliams13]

Thanks for the advise guys.

Paul, I will definitely check my design for deflection of the steel beams. Thanks for the link. I will definitely be overbuilding the structure, and I am sure there will be improvements to make along the way.

Jerry, you make a very good point, I realize the enormity of the task ahead and the numerous potential hangups along the way. However, my business plan centers around the CNC router and my ability to produce numerous variations of boards quickly and efficiently. My plan is to not follow the industry standard of creating a model line and producing tons of each model, but allowing numerous options to be chosen by the customer. Every board will be custom made for each person with their ability to choose width (shoe size), length, stiffness (core thickness) as well as a few other options as far as sidecut radius ect. I am going to have a huge amount of files for every possible permutation, and need to show that I am capable of producing these variations quickly and efficiently. Most of the initial funding I will be asking for in february will be to build more required manufacturing equipment myself, including a heated graphic sublimation press, second cnc router, and other tooling I have been designing. So showing my engineering ability is also extremely important. If I cannot make the february deadline, I am sure I can postpone, and my potential investor knows I am in the very beginning stages. For now I am gonna jump in head first and see what happens. Wish me luck!

[Rswilliams13]

Originally Posted by ger21 It depends on the drives you use. The most popular combination with that r&p setup is the Gecko G540 with 381oz motors. They'll outperform the 425's with the G540 due to their lower inductance.

Thanks for the info, I looked into those, but unfortunately they seem a little out of my price range. Do you think the standard 425oz/in 4 axis kit with the KL-4030 Bipolar drivers from keling will perform well on my setup? Thanks, Ryan

[ger21]

If you're going to spend $500, then it's well worth it to spend the extra $75 on the second kit here:
Page Title
The 425oz motors require a much higher voltage than the 3891 oz motors to get similar performance.
Be aware that the 425 oz packages have lower voltage power supplies (24V and 36V) than the G540 (48V).
My guess is that the G540 package will give you much higher top speed.