Thread: My Junkbot

G'day all,
After being away from the forums for some time, I have decided to make more of an effort and try to contribute more and encourage people who may be considering building their own CNC machine.

I have never really seen another CNC cutter or miller working except for a few U-tube vids. Since building mine I have seen two CNC plasma tables up close and personal, but don't know anyone who has a CNC router, although I believe a cabinet making shop in town uses one to make kitchens.
Whether this has been an advantage or a handicap in designing my table, I am unsure. The main priority was to build a machine on a very low budget as proof of principle and then upgrade with a new build, which I am still aiming towards.

This meant using whatever components I could scrounge and recycle, and being a Mechanic on week days, most of the components are used car parts, hence the name JUNKBOT. Due to space constraints I designed a usable bed area of a half sheet (1200mmx1200mm) and Z travel of roughly 150mm.

Originally the main purpose was to use my plasma cutter to cut shapes from sheet metal, but I tried to design it to be as universal as possible. Good thing I did because I soon found out that Junkbot with its unshielded cables all leading back to a computer doesn't get along with High frequency start on cheap chinese plasma cutter.

So I mounted my dremel on it and tried a small 3D carving in a MDF scrap, and found it worked quite well after a few teething problems.
The dremel was a bit slow and underpowered, so I proceded to mount my full size makita on the Z. This yielded quicker although often frightening results, as the stepper motors would stall long before the router, and the Z struggled to pull out of heavy cuts. This meant that while the controller would think it had lifted at the end of a cut the bit was still buried in the timber then it would plunge for the next cut and the now smoking bit was driven even deeper and all the axes would stall at once. On one occasion it actually stalled the bit, sending a shower of sparks from the collet over a table piled with fresh sawdust.
My first advice to anyone building a sizeable machine INSTALL AN E-STOP. Mine has had quite a bit of use.
Eventually I picked up a second hand trimmer cheap and found a happy medium there. This was recently upgraded to a makita die grinder.

Components used in this build should be fairly easy to gather if you can befriend a local mechanics shop, as most of them are throw away items from normal servicing.

I used - 3 timing belts two of mine are Subaru the other is Hyundai
- 3 cogged idler pulleys (Subaru)
- 1 scissor jack (easy find at any wrecking yard)
- Whipper snipper flexible drive cable (try your dump shop)
- 6 micro switches (donor microwaves)
- 2 slack adjusters (these are used on truck brakes I bought mine new for $20ea) to build worm drive reduction boxes.
- 19 flat timing belt idler pulleys
Motors and power supplys came from ebay.
Controller from Geckodrive (G540)
Computer $100 from dump shop
Old computer tower case
E-stop expensive but vital
Some of the steel was bought as well as some bearings and shaft.
Two 48v relays to match power supplies were kindly donated by a sparky mate in exchange for some automotive assistance.

I spent 12 months gathering most of the parts and about 2 weeks solid putting it together, and more hours modifying since. There were many compromises to allow for design around what parts I had to hand, but I am quite happy with the performance and accuracy.

I have carved photos, 2D pictures and 3D pictures on Timbers, plastics and aluminium.

Hope someone finds this usefull, and If you have been considering building GO for it! If I can do it you can!