Hi From Hereford

[fwm891]

I've purchased the plans for the 5 cnc machines at the above link really to get a better idea about how things go together and try and assess the choices made in the different designs (fixed or moving gantry's). The 18 x 24 moving gantry machine ( https://solsylva.com/cnc/18x24x5.shtml ) uses a rack-n-pinion for the long axis. I'm not sure if that has been done on a cost/availability basis or for a given accuracy - would welcome others thoughts on that. If a rack-n-pinion is a favourable option are there good/better R&P's ?

[Clive S]

Francis I take it you just jumped in and bought the plans without doing any research or reading the build logs in this forum.
I believe that you wanted to do intricate work I don't think you will achieve what you want to do with this machine.

Contact Wal and he will give you some good advise on what is needed to use 0.5mm end mills. The machine has to be rock solid to do this.

[fwm891]

Francis I take it you just jumped in and bought the plans without doing any research or reading the build logs in this forum.
I believe that you wanted to do intricate work I don't think you will achieve what you want to do with this machine.

Contact Wal and he will give you some good advise on what is needed to use 0.5mm end mills. The machine has to be rock solid to do this.

Thanks Clive, Yes I bought the 'plans' (detailed descriptions really) - $39 for all 5. And I've contacted Wal. I'm also looking at build threads in MYCNCUK too. I'm not anywhere near ready to start building yet (I'm way to green ATM) just trying to soak up info from different sources on different machine configs.
I'm beginning to look for different things as the research progress', I'm definitely still looking for something that will give me the small scale detail for the inlays and their housings (15 x 15 cm work area approx), but also looking at larger scale (for me) where something in the 60 x 45 cm size would be ideal but not require the same degree of accuracy.
I have a Myford speed 10 lathe and quite confident in my ability to make up smaller turned parts in non ferrous metals, even using it for some basic milling ops. Given the range of ali extrusions available a solid framework for a smaller cnc 'should' be fairly straight forward. The devil is going to be in the detail to remove backlash and provide smooth, controlled traverses along all three axles.
The more I'm looking at machine designs here the less inclined I am to just buy a ready to go jobbie.

Many thanks for the replies - all noted. Francis

[Neale]

... uses a rack-n-pinion for the long axis. I'm not sure if that has been done on a cost/availability basis or for a given accuracy ...

Just from a couple of things you have said - dimensions in inches, not millimetres, R&P not ballscrew - I would immediately say that this is a US design, even without knowing anything anything else about it. I have a theory that the Americans like R&P because it means that they don't have to use ballscrews, as the best price ballscrews of appropriate quality come from China. Ditto preference for Gecko drives over Leadshine - US not China. I'm not going to make any comment about the Gecko/Leadshine question as I've never used Gecko, but ballscrew for this size machine knocks spots off R&P which is really quite difficult to set up and maintain. It's not as easy as you might think when you take the necessary motor gearing, anti-backlash, etc, problems into account. None of these are insuperable, it's just that there is an obvious and easier method until you get to quite large machines.

[JAZZCNC]

Don't waste your time with any of those designs they are Junk.

Many better-designed machines can be seen on this forum that uses correct components for machine size. R&P is not a good choice for a small machine and really only used on much larger machines for specific reasons which won't get into now.

Unfortunately, there are no shortcuts to a good machine. Likewise cutting corners by trying to save costs is also not recommended so be prepared to spend a reasonable amount for good machine.

Best advise is Don't buy anything, NOTHING not even plans, until you are sure the design chosen is correct for your needs and the components are suited to the machine. So Plenty of research is the first move. Then start build thread to ask questions. Then ask some more questions. Then finaly you should end up with design and knowledge of whats required to build it.

Good luck don't be afraid to ask.

[fwm891]

Don't waste your time with any of those designs they are Junk.

..... Good luck don't be afraid to ask.

Noted - but don't agree that the plans are "junk" the machines portrayed in the plans serve a purpose and have been put together for a budget conscious builder (as a pensioner I include myself in that category). I'm not fooling myself that they're super accurate machines but not every piece of work needs to be done to the 'thou' sometimes ± 1 mm is close enough. As the research goes on I'm finding that I probably need a smaller 'accurate' cnc and a larger less accurate one...

Francis

[fwm891]

Hi folks, I've been doing a few things: looking at commercial desktop machines and how they go together, looking at build threads and how they evolve, looking at some of the rebuild of the Chinese stuff and doing some parts costing. Initially looked at linear bearings and tracks for the Y & Z axii, motors, lead screws etc., even though I'm looking at a quite small machine the cost is rising sharply. Sharply enough for me to look as supported rails rather than linear bearings/tracks. Not looked at the electronics yet. All part of the learning process, I need to take more time. I was hoping to get this project going quite quickly but I think it will be a few months before I pull all the bits together ready for assembly.

I'll put some of my drawings up for discussion over the next few days to see if my thinking is in the right direction. Still looking at a fixed gantry with moving bed. Twin support rails under the bed (Y) and across the X axis and paired rails on the Z axis...

Not decided yet on the type (diameter or pitch) of lead screw for each axis but decided not to use toothed belt drives.

Cheers
Francis

[JAZZCNC]

Noted - but don't agree that the plans are "junk" the machines portrayed in the plans serve a purpose and have been put together for a budget conscious builder (as a pensioner I include myself in that category). I'm not fooling myself that they're super accurate machines but not every piece of work needs to be done to the 'thou' sometimes ± 1 mm is close enough

Ok well build one then.!! . . . Some times folks have to learn the hard way.

[fwm891]

I'm going to move design thoughts over to this thread: http://www.mycncuk.com/threads/11661...neral-thoughts to avoid confusion and flow...

Francis

[JAZZCNC]

Ok well build one then.!! . . . Some times folks have to learn the hard way.

Hi Francis,

Sorry I fired off here a little quickly here but sometimes folks need bit of "shock n awe" to slap sense into them.!

You are obviously the type to buy on impulse otherwise you wouldn't have bought those plans in the first place. Anyone who had done any decent amount of research would have quickly seen the flaws in those designs.

Cannot stress enough the importance of doing the research which unfortunately means trawling thru threads and lots of reading.
Now sadly many don't want to do this so instead prefer to cut corners like with kits etc. We here on the forum know this recipe for disaster and wasting money.
So WE and I try to steer people away with our advice which has been accumulated while doing our own due diligence and over many years of building and using machines like in my case.
After many years of doing this you get used to people ignoring advise and doing there own thing. Which is perfectly fine that's there choice.
However now and again someone, You, in this case, will catch me on an off day where I just think "Stuff You" learn hard way.
Now You'd think after all this time I'd learn to just think it rather than say it but I've always been FIK got me in loads trouble has a Kid...Lol

So please accept my apology for being so blunt.