Thread: Chris's 2nd Build "Big K4huna"

Hi Chris,
No big deal about the beams and as you say shim the table flat. You have a very strong structure so you can do this with the confidence that it will not be flexing.

Everybody has to shim or otherwise adjust the table top to be flat anyway. If you haven't got one then get a dial gauge as this will help you.

Look for solutions and not the problems as it is a good build and well worth finishing.

Long time no update, been busy with work I hate working even thou I probbaly have it the easiest.

Finally got around to drawing up the designs and cutting them out, my router is far from accurate but it came out alright. About 5 prototypes and the last one only had wrong hole sizes which I just drilled out.

I noticed that my Z axis had dropped overnight "Once thought a brake was pointless"

Some PICS


BTW rod im watching your Mill build it looks interesting.

Hi Chris,
Now you are getting somewhere. Having an axis mounted and moving is a great incentive to pick up the pace.
I take it you will make the gantry sides from aluminum now you have the pattern.

Originally Posted by rodm

Hi Chris,
Now you are getting somewhere. Having an axis mounted and moving is a great incentive to pick up the pace.
I take it you will make the gantry sides from aluminum now you have the pattern.

My current cnc router is not rigid enough to cut aluminium. So when the Y axis is completed I will have to see if I can get someone to cut me some aluminium in either 16 or 20mm plate. That way it will be accurate.

Tried getting alu from the recycling place 4 times now and they always end up saying its gone.

Keep trying the alloy sides are worth waiting for

Looking good now chris...

Chris,
I just went back and looked at your photo's of the gantry ends mock up and was wondering if you might have another look at their design. I like the way Rod has his channel for his e-chain mounted so that it clears the Y axis 'box' around the Y axis alum beam. If you added some height and width to your gantry ends, they could easily carry the e-chain channel.
I did not think that far ahead, but because I liked the idea, I have designed a couple of 'e-chain risers' to fix on top of my gantry ends to support the channel. The attached picture will hopefully show what I am doing, but the drawing has become very much a working drawing with lots of things being shown in 'x-ray' form just so I could see their relative position. Hope it helps.
(Sorry the PDF is not of final design ... will upload correct drawing later ... have to go to work!)

Cheers,
Alan

Originally Posted by Zoot

Chris,
I just went back and looked at your photo's of the gantry ends mock up and was wondering if you might have another look at their design. I like the way Rod has his channel for his e-chain mounted so that it clears the Y axis 'box' around the Y axis alum beam. If you added some height and width to your gantry ends, they could easily carry the e-chain channel.
I did not think that far ahead, but because I liked the idea, I have designed a couple of 'e-chain risers' to fix on top of my gantry ends to support the channel. The attached picture will hopefully show what I am doing, but the drawing has become very much a working drawing with lots of things being shown in 'x-ray' form just so I could see their relative position. Hope it helps.
(Sorry the PDF is not of final design ... will upload correct drawing later ... have to go to work!)

Cheers,
Alan

I plan on having the Rack up top with a Guard which I will make later out of perspex which will just slot through the extrusion channels, I believe the top will be the best as I can just get some of that tape that has been mentioned a few times here to hold it down, but it will need to be protected because of dust.

I was planning on having the E-chain Behind and low, how I will attach only time will tell.

attached the rails, aluminium is so easy to drill and tap, the drill bit does not wander at all

The rails are 4mm from the edge.

I lost all my 5mm taps from when I did the steel so I could only tap 1 side as the tap I had was my dads one but it was only a starter.


I have been thinking of just using the 425 oz-in Nema 24 motor for the Y axis instead of the Nema 34 as its a massive motor and I dont think it is really needed now, was just thinking because my other router has a 269 oz-in and it has quite alot of force on its own, with a measly 2:1 ratio

Finished playing my game at 2:30, had nothing to watch so I just broke out Sketchup and started on my Y axis.

Its slightly different from what I was thinking as I wanted to have a cover for the rack but now its the only problem, also if the 60t Pulley will fit in there but im pretty sure it will or slightly hang out. Will probbaly need to think of how to make a tensioner also but I dont see it being a big issue.

Its basicalled boxed off as much as possible to make it rigid, everything will have to be precise as it is not sping loaded, not sure but in this case would a antibacklash pinion be suitable?

So not sure, does anyone see any problems with my thinking? any idea on a solution to cover the rack?

Just thought id see if a bunch of minds is better than a half asleep one. + everyone loves seeing pictures




*** Most of it is 16mm thick with the sides being 6mm and that plate in the middle being 12mm as its the thickest that would fit I might have to even go 10mm, but its job is to only hold the shaft and will only have upward force.

Far from the 60t pulley but I settled for a 30t pulley for a 3:1 reduction.

Chris,
Concept looks good ... darned if I can work Sketchup!

I have gone for ballscrew on Y axis with no reduction, so am curious as to whether it will work and at what speed. With your idea, I do have an alternative if my system does not work.

I was hoping to get some more done, but have to go to Melbourne for a couple of days!

Cheers,
Alan

Hi Chris,
Can you give me an idea of a supplier for the rack and roller pinion please?

Project looks awesome, keep posting pics.

Steve

Originally Posted by stevejw

Hi Chris,
Can you give me an idea of a supplier for the rack and roller pinion please?

Project looks awesome, keep posting pics.

Steve

Linearbearings.com.au
or
tea.net.au

Tea was slightly cheaper than linearbearings when I bought my rack, they will also stock pinions to suit.

Thanks Chris,
Can tell me if your rack and pinion is a roller pinion or just standard toothed pinion.

Thanks for the quick response.

Steve