BUNOZ-CNC Another Aussie Adventure

[Denbo]

"A CNC what..?", was what my wife said when I told her about some hair-brain idea to build my first machine. Closely followed by "how much!!$#?" and several other expletives.

Well, it's really not that long ago since I saw my first video of a homebuilt CNC in action. That fateful day set everything in motion I suppose. The mind started churning and the flame of desire for one of these computerized marvels went from a small pilot light to a roaring inferno the more I read and researched.

So the decision was cast, a machine had to be built, but it had to be done on a fairly tight budget. I looked at a few homebuilt designs that were out there and I was all ready to go with something similar to a Rockcliff design using these fancy linear bearings I've read so much about. (Cough), that was until I got the quote for the bearings

My CNC dreams came crashing down in a big heap. The cost for the bearings and screws would have cost me close to 2 gorillas and that was before considering motors, controllers and all the other bits which make up one of these monsters. Quite simply, it was just way too much for my first CNC rig.

Unfortunately in the land of Oz, we don't have the multitude of vendors and suppliers which a lot of you guys can source your components from. So I shelved the whole idea for a while but the concept never left my mind.

Here in Australia we have a hardware store called Bunnings - its pretty much all there is anymore, but anyhow.. I find myself going there - a lot. Whilst there I ended up with the dream to build a machine using materials which I could source locally (mainly from Bunnings). A design started to take shape in my head and eventually I got to a stage where I had to start putting things together in the computer.

I know what you're thinking here.. he should have just gone with one of the many designs that are out there. Yes, you're right, but somehow I never seem to do things the easy way. I also set myself a few goals; these were:
1) I wanted a machine which was large, sturdy and scalable
2) The machine would need to be a flying gantry type so I wouldn't be constrained by height
3) The whole thing had to come in at around a $1000 aussie smackaroos
4) Most, if not all components had to be sourced locally.

In the spirit of my design goal number 4, I wanted to get my motors and controllers from an Australian supplier. I can't begin to explain the frustration in trying to get the right information and bits at the right price. In the end, I've gone with a plug & play 4-axis system from Xylotex using 425oz. motors. The fact that the AU$ was trading strongly against the greenback and fact that the xylotex system was ready to go straight out of the box had me sold. Have to say I can't regret going down that path. For under AU$700 I had all the electronics and motors, leaving me with around 300 or more to spend at Bunnings on build materials - happy days

So after much sweat, cursing and tears, I'm happy to say that I've finally finished the design on the computer and can start the build process now.

I'm sure I'll stuff up a hundred (maybe 101).. times along the way, but I'm starting to enjoy this little project. I'll post pics and stories along the way, but for now, here's a couple of drawings out of the puter.

If by any chance, you stumble across my sorry tale, look at my design and go "Ach du lieber Gott! What's he doing it like that for.. " and so on and so forth.. then please feel free to comment, contribute or make suggestions at will. I'll take all manner of comments on board and hopefully I'll come out the other end of this whole process with a machine that does .. well .. uhm.. something.

Here's the main design.


The main construction is MDF and in critical areas, clad and reinforced with aluminium. The rails are alloy as well with slides that are designed using standard ball bearings and a mechanism to allow for adjustment against alloy inconsistency, build errors and to to pre-load the bearings.

[Denbo]

Today marked the start of the physical build process. No more gazing at the screen it was time to print out some drawings and head into the workshop - yay!

All bits there and accounted for.. check (well uhm.. at least I think so). Good grief - look at all those bearings..



I have to say it was good to get started on things and first on the list of things to do was x-axis rail number 1. No real problems so far. The whole thing went together very well and although I took my time with it, I'm sure the others will be a bit quicker as I get used to repeating the process 3 more times.

So at the end of day one we have:
- One complete x-axis rail assembly (pic below) and,
- one of the bearing slide blocks (of which there will be two per rail.



Tomorrow's task is to build the other x-axis side, make more bearing slides and hopefully complete one of the rail slide assemblies.

[Regnar]

Nice progress for day 1. I was wondering what are you using to attach the pipe to your beam?

Also I noticed that you are using washers to space your bearing away from the angled aluminum. I would suggest just using another nut and not to use any washers because you don't want the washer coming in contact with the sides of the bearing and binding it up. If you have to shim it out even further go nut head, angle aluminum, washer, nut, bearing, nut. Good luck.

[epineh]

Hey Denbo, looks like you are off to a flying start !!!

Great progress so far, it seems you have done a "little" research

I see in your profile you are in Qld, I don't spose you are further north than Brissie ?... I am waiting for the day we get somebody joining in the fun who is a bit closer to the pointy bit, just south of Cairns myself.

Welcome to the zone !!!

Russell.

[Denbo]

Originally Posted by Regnar Nice progress for day 1. I was wondering what are you using to attach the pipe to your beam? Also I noticed that you are using washers to space your bearing away from the angled aluminum. I would suggest just using another nut and not to use any washers because you don't want the washer coming in contact with the sides of the bearing and binding it up. If you have to shim it out even further go nut head, angle aluminum, washer, nut, bearing, nut. Good luck.

Hi Regnar

Thanks for your comments. I've posted a couple of pictures below to illustrate how the channels are put together. The illustrations are for my z-axis, but the assemblies are the same throughout. The tube is basically mated to the alloy base by self tapping screws. This is then mated to the other angles using 3mm bolts and then finally secured against the MDF using 16mm screws. The first assembly turned out very solid and the only flex I'm getting is on the rail upright (something that should be sorted when the whole x-axis gets assembled and mated together).

With regards to the washers, I've made sure that they fit snug around the bolt so there's no chance of them making contact with the outer race. Initially I was going to use a collet for spacing, but the washers I had were a perfect mate so I'll go with that for now and see how things go.

D.

[Denbo]

Originally Posted by epineh Hey Denbo, looks like you are off to a flying start !!! Great progress so far, it seems you have done a "little" research I see in your profile you are in Qld, I don't spose you are further north than Brissie ?... I am waiting for the day we get somebody joining in the fun who is a bit closer to the pointy bit, just south of Cairns myself. Welcome to the zone !!! Russell.

Hey Russell

Nice to see a fellow Qld'er on the board. I'm in Brizvegas - so I'm afraid were just about at opposite ends of the state. Thanks for the welcome though.

D.

[nev25]

Originally Posted by Denbo Unfortunately in the land of Oz, we don't have the multitude of vendors and suppliers which a lot of you guys can source your components from. Here in Australia we have a hardware store called Bunnings

I understand your frustration about suppliers
I'm in the process of building a modified JGRO machine
I was quoted something like $20K for steppers and controller (admitably they said it was for industrial applications not hobby)

I'm wondering where you got specialized items from (lead screws etc)
and what did bunnings have to offer.

I did see the local bunnings had a threaded rod that I was going to have a look at using as a lead screw but I don't think it would be suitable

[Denbo]

Originally Posted by nev25 I understand your frustration about suppliers I'm in the process of building a modified JGRO machine I was quoted something like $20K for steppers and controller (admitably they said it was for industrial applications not hobby) I'm wondering where you got specialized items from (lead screws etc) and what did bunnings have to offer. I did see the local bunnings had a threaded rod that I was going to have a look at using as a lead screw but I don't think it would be suitable

Hi Nev

The irony is that the industrial and very expensive stuff is probably easier to find than something which is cheap yet usable. The company "Linear Bearings" has ball screws which I was tempted to get. Their rod is close to 200 dollars a meter though and if you want a platform nut you can add about another 400 on top of that. I'm sure the stuff is gold but so is the price.

Bunnings didn't have the threaded rod I wanted so I got 1 meter lengths from a place called Boltmaster. They are standard M8 rods - straight, cheap and they look fine, but I'm sure they won't be as accurate as ACME or ball screws.

I want to see what kind of accuracy and reliability I get out of bog standard components before I tear a hole in my wallet for the high precision stuff.

D.

[crocky]

Good to see another aussie CNC being built and it looks like you have a zylotex kit for the steppers and controller

Keep up the good work!

Bob

[Denbo]

I suppose you're wondering where day 2 & 3 went huh?
Well.. its been slow going. On day 2 I only had about an hour of work on the second x-axis rail before my bandsaw decided to go belly up (Groan!)

Day 3 was pretty much spent hunting around for a new saw after I decided the old one was overdue for replacement. Spent no time at all on the build of the CNC (bigger groan!). One good thing though was that I got a big chunck of Delrin for 20 bucks from Eplas. The Delrin will be cut into blocks and sit on the screw blocks to move along the threaded rod.

Ahh.. up to day 4.
I've managed to finish the 2nd x-axis rail. A quick check - hey would you believe it, they're even level


Now to the slide assembly. The drawing of this was already posted above, and I approached this with some trepidation as the slide is possibly the most complex bit of the whole design. Lots of drilling, routing and double-checking but I took my time with things and luckily I didn't encounter any major problems. One change I made was to bolt the side angle plates onto the top and bottom slide instead of using screws. The MDF can and will split all too readily. I doubt I'll build in MDF again - would probably use ply if any wood at all.

Well lets not muck around then, .. here's the bits of the slide assembly coming together and being preloaded against the rail. Whole assembly slides very nicely and had zero play or movement.


Oooh this is getting exciting now - another slide will have to wait until tomorrow. Once I get that done I can finish the front and back plate of the x-axis and mount the first motors. Lets just hope no more tools break in the meantime.

[Elwood70]

" 3) The whole thing had to come in at around a $1000 aussie smackaroos"

Hiya Denbo,

Looks like a great project on the way there. Masterful use of CAD to make the original designs. Must have driven you crazy at times using Bunnings derived materials - switching from metric to imperial and back

Just wondering... Has the purchase of 'supplementary' supplies [eg. Beer - Pizza] pushed the project over the top of your original estimate?

Elwood

[arvindk]

Greetings Denbo
I am really in full agreement with your remarks about obtaining stuff in our "clever country" ! I too wanted a low-cost router/mill that I could cut my teeth on so to speak. I am a newbie, and in my retirement, funds are not limitless. I actually have a Sherline 2000 mill, but do not want to ruin it by my inexperienced efforts. So I thought I should look for ideas in the CNCzone.
Full marks for your enterprising work, I will be following this thread to lap up the benefit of your experience and progress. Could you please post some dimensions to your drawings, although I can get a rough idea from the pics ? Also when you get to using the Xylotex parts, please post your experience/opinion of that setup.
Wish you were south of the border though, I'm in Sydney.
Thanks and more power to your elbow.
Arvind