Z axis rigidity

I have the same issue, I think it a combination of the bolts, bearings and wheels.

The only solution I can think of is using a piece of channel with the v wheels in the channel and the channel bolted to the x assembly with v wheel bolts through the existing holes. So that the vwheel Botha are supported both ends.

I bought my ox as a kit from robocutters so I reserve the right to be dissatisfied with his kit as it wasn't cheap. Definitely areas which should have been rectified by now.

I too was told to bolt the x profiles, which I did aswell as epoxied, this helped initially but soon found that the flex here before was preventing further flex in the z wheels, so with less flex in x more strain went into the v wheels and Inturn the flex lost in the x was regained in the z. Though I think In a bid to rectify the issue the x will need bolting as well as a fix for the z.

 

I too bought a CNC kit from Robocutters.
Turns out to be £2,300 worth of junk!!!

 

ouch. Yeah Colin's designs where he's doubling stuff up is not enough to sell the size kits he makes.

Which kit did you get?

was there missing parts?

 

I was missing LOTS of parts. I lost count.
I also can get a refund!!
It is a very flimsy and weak machine. It needs much much more bracing. At my expense.
Shame as I had lots of orders.
Back to the hand tools!!;-)

 

That's typical of Colin, 6 month wait for me from him.

Get the refund, or credit and use Colin to source the parts for something stronger like a h or I beam version .plenty of guys here that can cut the plates for you.

£2300 could quite possibly build the strongest 1500x 1500 ox yet

was it the rediculous 8x4 machine he's selling by any chance?

 

You guessed it!!
CNC was, is new to me and a great addition to my furniture business.
Or so I thought!
He won't refund me as he does not have my money.
I'll use bits from what I have and re design it;-)
I did build a 2x3 solid box section frame. Is the best bit there. 2mm out on corners and flat as a pancake'!;-)
I may ask your advise when I start designing the new one. If that's ok?

 

That guy should loose his openbuild merchant license for the way he operates his business to be honest.

No problem. Happy to advise.

 

I agree. And thank you. It's good to know some one is on my side.
I checked out your website. Pretty cool.
And loads of joints!!!;-)
Where did you get your CNC from?

Cheers

 

Thanks. It's my own ever evolving design. All purpose built around the idea of keeping Cnc affordable with Low overheads.

Though the 5hp atc that is the next upgrade may break the bank somewhat.

 

I have been waiting for a small ATC spindle I got on kickstarter for well over two years.... It is finally on its way down to NZ and cant wait!!!

 

Is that the atc cartridge? There is already a couple of other atc attachments, even one for kress but £500 each. How much the kickstarter one going for?

 

it was a project that funded quite a long time ago, you can now get the same out of china for less as I would not recommend the guy I got mine off... I have found it rather painful but glad after a 2 year wait its finally being shipped!

 

yes but if it the cartridge type it means it compatible with any spindle that you can fit a pulley or coupling which is nice.. id say its more for vertical mills tho than routers as your now bolting the cartridge and spindle either side by side or direct drive, and adding a fair bit of weight doing so and having direct drive your spindle center of gravity is higher which isnt such a good thing. kind of tempted tho as it looks more robust than the chinese versions.

id hope not to wait 2 years tho!

 

I see colin has withdrawn sales of his larger "stronger and better" ox design., cant recall what he called it, probably because it was pants.

 

I have an idea to strengthen the Z axis! I just have to test it and/or design a little something...

 

having the vwheel bolt supported at both ends would help massively.

 

Look at this! It will help a lot! Do it on both side

 

I added a 4th wheel on each side. Prototype here: http://www.thingiverse.com/thing:1015574
Helped a bit, but thinking the different axis wheel is a better idea.

 

Im thinking this would help as leaving those bolts unsupported really isn't good: Ignore the scale its all wrong.



if any one wants a set of two of these i can mill from solid aluminium bar for £10 per set, scale and holes to match ox plates corrected or custom. can ship anywhere from the uk.

 

Nice cassette concept

Any pictures of a completed set? Have you installed them on your own OX?

 

Lol no it's on my never ending list of to do's and hadn't recieved much interest to mill any, but I have ascertained that it can be done simply by sandwiching a solid aluminum square bar between two rectangular bars. Can't quite recall the dimensions of each but holding a vernier up to your machine will tell you the thicknesses you need you just have to keep in mind the wheels require ideally two washers either side between bars. And some additional holes through the solid part of the sandwich would be required to bolt them all together.

Failing that I would be happy to mill some up from a single bar for you, Wheel placement and wheel bolt holes the same as original.

Think it's without doubt that a lot of the flex in the z is caused by spring in the unsupported wheel bolts, infact mine have begun to bend, so this would eradicate the possibility of this issue.

 

I know exactly what you mean regarding never ending list of improvements!

To be honest I was thinking a solid block of aluminium with a pocket for each wheel and a taped hole for the LP screw would be by far the most solid way of combating the flex. The only part I'm struggling to picture would be the opposite side with eccentrics! Could even incorporate Danny's rear support wheels in the cassettes. These cassettes would nicely fix to the current X-axis plates as a modification for strength though!

 

Ahh yes the eccentrics, sorry forgot about those, I've actually designed a block that allows for the escentric spacers, it also has access holes for each spacer individually for adjustment and the outside holes (bolt tip holes) also have eccentrics.

A neater option would be to have adjustment on the entire block instead of each wheel individually. I'll get the design up of the one with escentric and see if I can come up with a simple way of adjusting the entire block instead as soon as I can.