Thread: CNC Build - CH1

Well I managed to get some work done on the bearing blocks.

After following Rods instructions I have seemed to have the Z axis bearing mount working great and it spins nice and freely with out any effort at all.

The X axis is another story, its almost as though the rubber is too tight for the spacers, even when you try to rotate between your fingers (pinching each end) or with some leverage its locked up tight.

I might try and remove the rubber flanges and maybe lightly sand the inside of them, not sure if this may free them up a little.

I take it these rubber flanges are really just to keep the dust and metal out and protect the bearings so i go carefully.

Cheers
Glenn

Hi Glenn,
A follow up on this I did a bearing block last night and found that the oil seal was too tight on the steel bush. First I took the steel bush out and polished the outside on my lathe with emery - you could do this by mounting on a bolt and using your drill.
I then noticed it was really hard to get the bush back in the seal. The bush needs to rotate in the seal so this would be a source friction. I used a sharp knife and relieved the inside hole of the seal where the bush runs and that fixed the problem.

Thanks Rod thats a great idea, that will most definitely fix the issue! I'll give it a shot tomorrow.

So I have been working on the gantry parts and focusing today on the Y axis plate that the rails will mount onto, lots of countersinking, tapping, countersinking.. tapping!

The guy I bought the aluminium off said it was best to go with 12mm as it is generally a lot straighter with less irregularities, although it still seems to have few ups and downs (+/-.5mm)

I was thinking that to mount the rails and ensuring they are 100% flat it might be an idea to route a flat section/groove to remove an irregularities.

As I only have a limited amount of tools I would have to use my small hand router to do it, and take light passes of .5mm.

I was going to make up a jig with two tubular aluminium pipes and use them as the router guide, I've attached a mock up pic to show you what i mean.

Does anyone have any experiences with doing this? is it worth it or am i being to pedantic with trying to get it dead flat?

The Y axis plate will be mounted onto some extrusion and locked on by the usual T nuts every 60mm, which should ensure the plate is at least flat.


Cheers
Glenn

Originally Posted by Lappy

I was going to make up a jig with two tubular aluminium pipes and use them as the router guide, I've attached a mock up pic to show you what i mean.

Does anyone have any experiences with doing this? is it worth it or am i being to pedantic with trying to get it dead flat?


Cheers
Glenn

how straight are your aluminium rails , and your clamping to a bench , how straight is the bench ,
unless the bench and rails have machining marks showing in the serfaces you are not going to get it "dead flat" ,
also heat will be a problem with hand held router , will work well in 5 sec bursts , once the carbide tip turnes purple from heat the ground look will turn into the chewed up and spat out over heated aluminium look ( not good)

Thanks Sawdustsniffer, rails pretty straight when comparing on various straight edges and bench is dead flat so i'll see how it goes, jury is still out. I do have a couple small rebates i need to cut first so i'm going to test on them and see how it comes out.

So a couple of days of marking, cutting, drilling, countersinking and tapping... and tapping and tapping (practice makes perfect thats for sure)!

So far have almost finished the gantry arms, undercarriage plate, Yaxis plate and Z axis plate. Also finalised the stepper mount for the Z axis.

I have started sanding some of the parts to remove any scratches etc to make it look a little more professional, whats everyones thoughts should I:

1. Give the ally a brush finish look
2. Highly polished mirror finish

Keen to hear people opinioins!

I'm leaning towards brush finish although polished could look kind of cool.

Cheers
Glenn

Made a little more progress today..

ended up going with just a sanded finish on the ally pieces..

so, put the main parts together on the gantry, seems to move ok on the rails with little binding, need to play around with things a little more though.

Gantry feels rock solid, no play or movement at all which is what i was hoping for!

hoping to get some done on the z axis done tomorrow if i get a chance.

Cheers
Glenn

Another awesome build in the works

They sure do go together quickly.

Hi Glenn,
Not surprised you haven't got any racking on the gantry. Are they 20mm plates and if so it looks like 4 passes at 5mm depth of cut - that is impressive. How do you cut them?

Keep the posts coming and I like your combination of t slot and plates.

Thanks Chris!

Rod, you have good eyes and great attention to detail! I actually went with the 20mm sides after reading your build log on Big G and how you reinforced the arms to stop racking.


I actually had someone cut them for me, (unfortunately I have a limited tool base mainly woodworking hand tools, drill press etc). The gantry arms were done on a big bed router, tell you the truth I didn't even notice it had been done in 5mm passes until you pointed it out.

I was going along well today hoping to assemble the Z axis, just as i was tapping a M4 thread it snapped I was obviously to eager to get it done.

struggling to get the thread out as when it snapped it was almost at full extension, not much left to grab onto either as it pretty well snapped flush with the hole. Also M4 is already pretty small to try and safely drill out.

Will need to think about it for a bit... maybe over a beer.

I finished up by doing some rebates in the Z axis in preparation for the stepper mount. I made a crude guide and used my edge trimmer with a 2 flute end mill making .5mm passes. I was surprised how well it cut!

Cheers
Glenn

Hi Glenn,
If the tap is in aluminum then this looks like a good solution (pun intended).
Just plug the bottom with plasticine or silicone and form a dam around the hole at the top. Check there is no reaction with the dam material first.
Here

hi Rod, thanks for the tip will be keen to try it out just need to fine some aluminum potassium sulfate! will do the trip around the chemist to see!
I think it will work a treat.

interesting site, i could see myself getting lost on there!

Cheers
Glenn

Managed to get a little more done this weekend, although I felt I was chasing my tail!

Realized I had not thought the design through as much as i should and had a little issue with putting the Y and X axis together. Stupidly placed the linear guide rails over the top of the others bolt holes (if that makes sense)

Ended up working a way around it after sleeping on it.

So I have attached the Y axis plate on the the gantry extrusions which has locked the gantry up even further, i just hope i haven't over engineered this and made it too heavy for the steppers to drive!

Also attached the rails for the Y axis and attached Y axis, movement seems ok although there is a little binding on one side. i need to work on aligning the rails better I think.

Anyway heres some pics of the progress.

Cheers
Glenn

Hi Guys,

Been a while since i have updated this thread, although i have been working in the background pulling my hair out with the electronics!

I managed to get everything wired up, double triple checked all connections with the trusty multimeter and everything seems to be wired ok.

Spent the last week trying to get the motors to respond to mach3 with not much luck.

I've been through a heap of trouble shooting info but something is not quite right!

So far i have confirmed in mach that all the basics also appears ok, ports and pins config etc, i believe this to be confirmed as on the breakout-board (homanndesigns MB-02-v6) you can see the LED's respond when moving the axis via mach. the only thing that may be a concern is that some of the LED's are slightly dimmer (specifically the dir pin) when compared to others (step)?, thats aside the above tells me that my mach settings should be ok.

Checked continuity on my stepper cables and they are all good.

power is getting to the steppers as they lock as usual also the 203V drivers power light is coming on and no other warning light etc.

I may be too close to this and not seeing whats directly under my eyes

anyone have any ideas on what i could try? or if their is something i have overlooked?

was hoping to have everything up and running this weekend but i think i may struggle!

cheers
Glenn

Is the Vcom for the BOB and drivers set correctly?

I remember some customers who setup the G251's would be stumped as to why their setup wasnt working, it turned out the Vcom was set incorrectly on their breakout board.