Beginner MYCNCDIY Mill Build questions

[JAZZCNC]

But that's exactly what he's proposing to do anyway, at least the ebay job is ready built and more importantly saleable again.

Not if he's smart and listens to experience talking and while Yes it will be saleable he'll still be losing money.!! . . . . If he saves a little more money he'll get exactly what he want's and when comes time to move on or needs larger machine he'll make money not lose.!

To me that's problem these days every body want's everything instantly but for nothing.!!. . . .Good things come to those that wait.!

[suraj1793]

Hi guys, my budget is around £400-£500. I was initially hoping to build something like this: http://www.mycncuk.com/threads/1541-...-framed-router and work on using it for carving and stuff like this http://www.youtube.com/watch?v=VhKl0...IyoicGWeJ5Z1gQ making use of roller carriages instead of supported round rails as shown here http://www.youtube.com/watch?v=5dmPV7TyzPg as precision is not a high priority for my build but not sure if this is possible with my budget. If not, I would be more than happy with a small router for carving work as shown in my previous post.

As mentioned, I can get box section (both steel and aluminium) and things like fasteners, welding equipment, sheet metal all for free from work. Also, I have an Arduino Uno which could run GRBL and connect directly to the drivers, so might be an option for a controller.

[JAZZCNC]

Well if you get all the steel and fastenings etc for free then you may and it's a very slim chance just about do it. . . .BUT . . . It will be compromised in performance and abilty.!
It will require great attention to detail when building to get even moderate accurecy. The inefficiency or the linear rails etc will require more power from motors to overcome any sticktion. Attention to little details of design like adjustments etc will be needed and you WILL constantly be chasing adjustments.

One problem with the bearing setup shown, and I have built like this so speaking from experience here, is that chips and rubbish become a problem with binding bearings. The bearings wear quickly so need replacing often, on upside they are cheap, but still a pain in arse.

To be honest to build anything like a decent machine that's worthy of the effort involved, which to be in no doubt is considerable, then £1000 is the minium needed to make it worth the trouble. If done correctly then your £1000 will earn it's self back in no time and really will be instantly in profit from day 1 as you could sell it for far more than it cost to build.!!

My advise as always in this position is save up and spend that bit more. Even of you buy a chinese router for £500-600 like Eddy suggest's then you'll end up spending £1000 by the time you have replaced the spindle and electronics when they die.!. . . . And they will sooner rather than later.!!

[suraj1793]

Thank you JAZZ!!! Given me the slightest of hope that this may be possible after all, although...after reading the rest of your post i'm not sure if that was your intention

Just to confirm, when you say I have a very slim chance of pulling this off do you mean for building my dream steel router that pavlo had built in his build log or a smaller desktop router?

From what I understand the main cost for my first build will be the electronics (drivers, motors, PSU, spindle) as the materials and parts for the frame I can get for free or build myself (including roller carriages and ACME threaded rod). As you explained this will compromise the router quality and performance ability however, do you think this will still be "usable" for some wood carving work as long as I pay a huge amount of attention to detail?

The positive I see in trying this out (if there is any ) is that if worst comes to worst, I have myself a decent set of motors, drivers, PSU and spindle and a router which cost me nothing but time to build.

Will start working on Solidworks models but do you think I should also start looking into the electronics now? In the build log he has used 3.1nm steppers, do you think these will still be OK with additional frictional load of the roller carriages as you had explained?

Thanks

[irving2008]

Not with ACME threaded rod, the friction is too high and the pitch too low to get any serious performance. You'll be measuring job time in days rather than hours for anything remotely complex.

[suraj1793]

Thanks for informing me of this. Are there any other decent alternatives to this? I am going to look further into the rack and pinion type setup but if all fails I guess I will just have to go for ball screws.

EDIT: I understand that this is real sloppy for a CNC machine and I will probably look like I have gone mad for asking this but I just have to ask, could a rack and pinion obtained from a small car steering rack work as an alternative?

[JAZZCNC]

Suraj, Forget R&P from a Car but what you could use and is the next best thing to ballscrews for efficiency are timing belts and pulleys. BUT again I can tell you from experience that by the time you have bought all the pulleys and idle gears etc then they don't work out much cheaper than ballscrews from china.

Completely Forget threaded Rod it's absolute waste of time.

If you try to do this on the cheap I promise you will regret it and the only useful thing to come from it will be the painful lesson that it can't be done cheaply.!! . . . . . Don't get me wrong I'm not trying to put you off building a CNC machine, Far from it, I'm trying to steer you away from taking the expensive cheap route.!! . . . . Seldome does it work out Ok and nearly all those that do succeed end up building another as the first has too many weak areas to be worth while upgrading.!

[suraj1793]

Thanks JAZZ, I appreciate you warning me of the expensive lesson that I may learn and think it would be silly of me to ignore such advice. So, I think it would be best for me to hold off on the mill until a later stage. However, if possible, I would like to continue learning about CNC and at least work on some form of a CNC project which may be more doable with my current budget.

Maybe a conversion rather than a build? I have had an old round bed drummond type lathe sitting in the garage for a while, very similar to this one (http://www.lancerregister.com/showthread.php?t=378816) but a bit bigger. Do you think that this would be a suitable CNC conversion project which would be doable with my budget? If so, hopefully it could be set up such that I could use the parts I buy for future builds (motors, drivers, PSU, etc).

[T0rnado69]

an interesting read this thread has been, and sort of reminds me on when i joined this forum
and wanting to build a dual cnc machine on the cheap.
and after getting much advice from the usual members, i decided to take the advice and not waste money on the expensive cheap route.!! ( as dean puts it :) )
and after seeing a picture of the mill i have converted to cnc.
i thought what a good idea.. so im saving up for good electronics.
that will serve me well and can be moved to another build later down the line if required.

[JAZZCNC]

i decided to take the advice and not waste money on the expensive cheap route.!! ( as dean puts it :) )

Yes strange statement but really is true. The difference between good and Bad electronics unfortunatly does kind of translate into Cheap or Expensive.
Again unfortunatly the Cheap route all to often becomes the expensive route and most anyone who as experienced the performance difference Good quality Digital drives make to steppers will tell you they are worth every penny. Equally anyone who as experienced the hair pulling head banging frustration of cheap nasty electronics will backup that it was an expensive lesson learnt.!

Put decent quality electronics with a good motion control card and you'll have hassle free machine that performs with the best of them.!. . . And will do it 24/7 for years.