# CNC Machine - for home-building aircraft

Discussion in 'Workshop Tips and Secrets / Tools' started by Rienk, Apr 17, 2015.

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1. May 17, 2015

### ScaleBirdsScott

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I've got no problem getting quality import stuff and yet I can see that for many companies even with some disparity in production cost, they don't see much benefit after all the other costs of export in marketing their high-end stuff to the USA: first they have to fight the negative image of cheap asian import, and second they have to compete with the domestic preference in higher-end goods.

I'll point to a situation that I went through recently where I was trying to decide on a 4" machinist's vise for my new desktop mill. I could go $150-200 for a cheap import vise from a variety of sources, I could spend$400 for a reputable US-brand that sells quality import parts (Glacern) or I could have gone with a full-domestic, known quality standard of Kurt for $550. On one hand, the Kurt stuff supports US industry and that's good, and on the other hand the Glacern would be almost identical in quality and utility as far as my concerns go, and$150 difference is enough to buy a nice set of collets.

In the end I had to go with bang for the buck so I went with Glacern, as they were offering something made overseas (I believe from Taiwan) to good standards, and charging enough less than the US-made equivalent to justify the savings. If the price difference was $50, I would have gone Kurt no question. Another factor that I will admit is that the Glacern is black and steel, while the Kurt is blue and steel, and the blue and steel matches the color scheme of my mill very nicely which would have actually been worth some price increase on top of whatever the other differences were. (The epilogue to that anecdote is that a week later I got an email from Enco with a 20% off code that would have dropped the price of the Kurt vise to be the same as the Glacern, and I contemplated putting the Glacern up on ebay for a few dollars off my cost, just so I could turn around and get the Kurt... but I held off. I may still decide to go that way next time one of those specials comes around... so if anyone wants a brand new Glacern 4" vise for a few bucks less than retail...) I've got zero problem buying import goods if the quality matches my needs for the cost, is the bottom line, and I don't mind buying something that needs a little TLC if the costs are worth it. But I also will pay extra for something that has the right fit and finish (and color scheme) if it's reasonably within a budget. 2. May 18, 2015 ### WonderousMountain ### WonderousMountain #### Well-Known Member Joined: Apr 10, 2010 Messages: 1,853 Likes Received: 192 Location: Clatsop, Or I could really go for this as I'm learning CaD for the purpose of making things. Of course, I could probably finish learning what I need to and make one of these machines in the time it would take to iron out the basics on this site. LuPi 3. May 18, 2015 ### rv7charlie ### rv7charlie #### Well-Known Member Joined: Nov 17, 2014 Messages: 435 Likes Received: 170 Location: Jackson In support of 'Chinese stuff can be good', I offer this: When I decided to purchase an AC/DC TIG welder a few years ago, I considered purchasing one of the 'mystery brand' Chinese models that are available almost everywhere, even the local pro welding supply shops. I couldn't bring myself to gamble on one, so I watched ebay until I found a nice used Miller solid state variable frequency unit for about 1/2 the new price. Works fine, has lasted a long time. But.... after purchase, I started seeing reviews by professional welders of the various Chinese models, with almost universal thumbs-up ratings. Basically saying, if you want to do high volume production work, it might be worth buying one of the 'big 3' American brands, but for all others, the Chinese stuff is just fine. Then one of my friends decided to scratch build a Cub. He bought one of the Chinese welders, brand new, with more features than my Miller, for about half what I paid for my used Miller. He's got the fuselage almost complete and loves the welder. And guess what; all the new 'big 3' solid state welders are made in Asia, too. Anyone want to buy a nice used Miller Dynasty? Charlie 4. May 26, 2015 ### autoreply ### autoreply #### Moderator Joined: Jul 8, 2009 Messages: 10,732 Likes Received: 2,542 Location: Rotterdam, Netherlands I have some difficulty believing that. Waterjetcutting runs from 1-5 euro's per square meter, dependent on complexity of the cut lines. Probably less for thin MDF. Might be hard to find down under, but shipping thin MDF is pretty cheap too. 5. May 26, 2015 ### ScaleBirdsScott ### ScaleBirdsScott #### Well-Known Member Joined: Feb 10, 2015 Messages: 1,033 Likes Received: 656 Location: Uncasville, CT I had a similar epiphany: it cost us something like$350 at a local wood remodeling/sign shop to have shapes cut from a single piece of mdf. It also took over a week because there was some kind of glitch where their software was having problems reading my particular files correctly, and someone in the process of converting my lines in CAM drug a spline improperly and a part was misshapen. So it took further time of at least a week to get a new one of those parts made after we realized it was off and tracing the issue back.

Similarly we had a water jet service cut a few sheets of aluminum for us and the result was parts that were very roughly cut, delays of weeks to get them cut in the first place, $150 min charge to do the CAM, and the price was somewhere around$100/sheet.

Given that over the scope of an airplane such as the one I'm designing it might require 10-ish sheets of mdf for forming and fixturing, and probably 20-ish sheets of aluminum to be cut out on a cnc, at a minimum id have to spend a few grand in shop fees, plus likely a grand more in CAM, and that's hoping I never have to change the design or remake parts and that I can afford 2-week turn around on a set of parts.

IF one has ALL the parts on file and they are proven aND it can all be done st once it might make sense to hire it out and they will probably be a better rate and can slot you in as it'll be a somewhat big job.

But the price ends up at best cancelling out with a cheaper router build, and the utility of owning the machine and being able to tinker is worth a huge amount on its own.

6. May 26, 2015

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That all sounds awfully expensive. DXF should solve the issue of CAM. We paid literally fractions of the earlier mentioned amounts. How come, great deal, or highly overcharged?

7. May 26, 2015

### Jay Kempf

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My guy doesn't charge CAM. I hand him a DXF it is always perfect. He even nests parts at the machine and adds shaker tabs if it is that sort of job without any engineering charges. But AR your prices are way low to the average that I see. It's about run time so it has nothing to do with price per square meter. It has to do with the part, the sheet, the nesting, the scrap scheme, etc... I have the experience to design parts and sheets to operate fast and reduce run time. Sharp inside corners are notorious slow spots and not good designs anyway for any sheet metal parts that are stressed.

But another question. How would you waterjet MDF. It isn't waterproof so you will wreck and stain it just cutting it. Same with any plywood. Laser or router is a better solution. My guy waterjet cuts under the surface of a shallow pool of water. That means all parts have to be cleaned after. Waterjet is great for glass, stainless, stone, aluminums, brass, plastic, rubber, and OK for steels that will be cleaned/blasted afterwards.

8. May 26, 2015

### Rienk

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There is waterproof MDF - but it's expensive!

We waterjet cut plywood all the time. The entire TS-1 was waterjet out of furniture grade Birch ply - we love the stuff!
The abrasive in the water does leave a stain (see photo), but that can easily be mitigated by purchasing plywood that is pre-coated with a light varnish, then there is no problem at all. Plus, with wood, the material is not submerged.

BTW, don't bother cutting regular wood with a waterjet - especially more than 1" material; the jet will follow the grain, and the cut will not be even close to plumb.

9. May 26, 2015

### Jay Kempf

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I guess your waterjet guy doesn't use a water bath. Mine does for all the materials we have specified so far. Not sure if he offers the service to empty the bath for ply. I'll ask him. Might be useful.

10. May 27, 2015

### Rienk

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Most newer waterjets have instant leveling capabilities, so they can lower and raise the water level based on the material being cut. However, other than glass, most thin material is rarely submerged.

11. Jun 7, 2015

### JamesG

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After 2 years of neglect after a move, I finally have my Tiag mini CNC mill set up, lubed up, and dialed in again! I don't have anything to cut with it at the moment. But its nice to hear it humming again.

12. Mar 21, 2016

### Rienk

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I'm BAAaack!

Amazing how bi-polar I am with the forum... on every night for months, and then don't even look at it for almost a year? Criminal.
I'm still moving forward (baby steps) with setting up a MakerSpace in my community, but haven't done much about sourcing an inexpensive CNC router yet.

Fritz, can you send me the information on yours (kit?) again? Thanks!

13. Mar 21, 2016

### FritzW

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Hi Rienk,

Welcome back. I'm been missing the action on HBA for a while also (tied up with a chapter Waiex project).

My machine is the old CNCRouterparts 4x8 with ebay steppers and electronics (1,600 oz/in steppers and a 2.6 kW spindle).

I just talked a friend of mine through building a 4x4 pro version. He's using smaller stepper motors and a router (smart idea, lessons learned from my overkill machine).

The machine has come in pretty handy on the Waiex project:

modified seat pan for the Waiex

I made a bunch of canopy latch plates for the gang on the Sonex group.

Rienk, the world needs a realistic home CNC machine to build the next generation of homebuilt airplanes with. I hope you come up with that machine

Fritz

14. Apr 18, 2016

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Hello All,

I just found this thread through the 21st century volksplane thread. I designed a CNC router a few years ago, but due to may reasons I never built it. I am considering reviving it and building it this summer. I originally designed it to help cut the parts for a Bearhawk LSA. I drew most of the wing in solidworks and made a few mods to the ribs to favor routing. Unsure if I will ever build the Bearhawk, but the thought of whats happening in the 21st century volksplane has me interested in this again.

I designed it with a useable area to route a 4' x 5' sheet. I figured, I could use alignment pins and move the sheet if I needed to route something longer. Below is a Jpeg from solidworks, but the Z axis is not shown as I was not finished with it.

I designed the Machine around the cheap ballscrews found on Ebay right now with all bearing journals from ebay or Misumi. Bearings are pretty big Hiwin rail and truck type. At the time, there was a site with a bunch of surplus Hiwin stock and they were crazy cheap so I designed it around what they had in stock. I plan to visit the site again to see what they have now and may have to make some design changes. Sadly I have a bunch of expensive THK rails and trucks, but none are long enough for my application and buying additional rails to use what I have costs more than the overstock Hiwin items. If I remember correctly all my mechanical and electrical components to build this was right around 2K. This did not include money to build a frame. I purposely made many of the parts without any counterbores and just through holes so as to be able to use each part as a left or a right. Also it allows most of the flat plate parts to be waterjet cut.

Marc

15. Apr 18, 2016

### Jay Kempf

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Have you sourced all the parts and come up with a price for your purchase list?

16. Apr 18, 2016

### Rienk

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Marc,
Any size bigger than 3'x4' would be useful, but being able to do full size sheets would be the most practical for any type of aircraft fabrication. Have you seen the Shopbot Buddy system with their 'Power Stick' option? That is what I think is the best way to go for the home shop CNC - a 24"x48" router table, with the ability to add something like the PowerStick option and do full size sheets; doing something similar for a few thousand dollars would be an incredible boon to the hobbiest/builder!
Here is a link to a three minute video explaining their system...

http://shopbottools.com/videos/Buddy and Powerstick 320x240.wmv

17. Apr 18, 2016

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Hello Jay,

I only priced out the mechanical items but with what was left, I was coming up with an estimate of 2K to 2.5K. All of that may be out the window now as I am unsure if the Hiwin surplus parts are still available. Anyone designing for something similar to a kit should design around not finding surplus items, but standard parts that would have a constant sell price. I could have designed around using Bishop Wisecarver V groove wheels and such, but rigidity is key in a machine and that system is not nearly as stout as a linear rail with a recirculating truck. V groove wheels are now available even cheaper now with the maker movement. Maybe I should rethink this design and go that route if I cant source the Hiwin rails, but I would be doing so at a cost of rigidity, but likely for cutting thin aluminum it may be OK. I have 20 years of experience designing linear motion platforms for the robotics, automation and film industry so I have done this quite a bit. I would like to run closed loop with Renishaw RGH24 linear encoders, but not everyone can afford those, but they can be found surplus as well.

Marc

18. Apr 18, 2016

### ScaleBirdsScott

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My table uses delrin v wheels on makerslide, and while it could be better, plenty better, it does do the job; and you can get a fairly smooth running, reasonably accurate machine for a low cost and minimal effort.

Ideal setup for the future will be linear rail and what not, but until then I'm able to make due with this setup and I'm cutting aluminum up to 1/8 inch. Just gotta take multiple passes and choose conservative speeds and feeds.

Not suited for mass production but if you're doing small volume it does ok.

19. Apr 18, 2016

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