To build or not to build...

[ilya]

I'm researching the CNC thing for some weeks and I'm at a loss.
First, however, I should tell you what do I need a CNC for: I'm planning to machine 19" aluminum front panels. It should be rigid and strong enough for this, and I'm aiming at the working size of 21"x12" minimum, Z travel is not that important, so it can be anywhere from 3" and more. The speed is not that important also, but it would be nice if I won't have to wait forever for the panel to be finished as I'm planning to run small batches occasionally.
Now, I've almost found the perfect machine for this, but unfortunately its X travel is 16.5 only, which means I won't be able to machine 19" sides during 1 pass. I suppose this is no good because the bit will leave a mark at the point of entry even if I use some fancy curved entry path (correct me if I'm wrong). The price of this machine is 2000€ which is ok with me.
I've been hunting for the information on the net about DIY CNC mills and most popular builds and plans are for wood routers that are kind of weak for aluminum. Some designs make sence but I need an access to another CNC to accomplish them, which I don't have. I've run accross the good supplier (worldofcnc) which appears to have almost everything needed, but again, they don't have any plans or DIY section with the info.
Do yoi guys know if there is something that will suite my needs? I'm looking for something that doesn't require complex tooling and is more like a kit or has easy to get parts. If absolutely needed I can find a local machinist though. The main question is should I start the build mess with 2000€ budget ready to be spent and would I get what I want for that? Or is it better to just get the machine and find a workaround for the X travel being too small?
I must add that I'm quite comfortable with electronics so this part of the build doesn't scare me. However my mechanical skills are not as good, I don't think I'll be able to design parts, at least in the reasonable amount of time.
Thanks for reading this. Comments and ideas appreciated.

[ilya]

Some thoughts so far.
I've found a great source of linear slides and ballscrews - motiontek.ca; I need a frame though (which I'm planning to build out of 80/20 stuff). And the overall gantry. The gantry is the biggest problem for now 'cause I have no plans and no clue how to build it. I also thought that I can laser cut steel locally, which is another good thing.
Hmmm.... Too many questions still...

[lovebugjunkie]

Have you looked at Joe's plans for his Hybrid.
http://joescnc.com/index.php

[Jeremy Harris]

As you've already been looking at buying parts from the UK, via Marchant Dice (the worldofcnc website) you might want to look at the Zapp Automation site, here: http://www.slidesandballscrews.com as they're generally better value.

I can't help with plans or a kit, but most fairly rigid (metal construction) machines should be able to do what you want, I think. Machining light alloy in light cuts isn't significantly more arduous than machining hard wood, so as long as you get a machine with the right sort of accuracy you should be OK.

Jeremy

[ilya]

lovebugjunkie,
Thanks for the link, didn't know Joe had got a site already. His hybrid machine is way too big for me, but I might use some design ideas from it.
Jeremy,
Thanks for your input. It would be ideal if the machine will be able to cut 2mm deep at one pass, but I don't know if 8020 stuff would be rigid enough for that. Zapp Automation is a great place! I might consider them because I haven't got any responce from worldofcnc (and this speaks for itself about their service and customer support).
Now I'm more and more into 8020 stuff. I really liked the Ahrens linear motion system for these profiles, and the whole product line of his shop is targeted at 8020 and makes an easy machine possible.
However I'm not sure if 8020 has a distributor here. I,m currently looking at Isel and Kanya profiles but I'm not sure if their dimensions would fit Ahrens parts.
I'm going to draw some models to see how it works out.

[Jeremy Harris]

My experience of Marchant Dice is that they can be a bit slow to respond and their prices tend to be a bit high. I think others have found the same. I've not heard of any real problems with them though, I bought my 12mm x 3 ACME leadscrews from them recently.

Zapp seem keen to help, Gary from Zapp often pops up on the very little used UK CNC forum, http://www.mycncuk.com/forums/index.php and is usually full of good advice.

I'm not connected with them in any way, but do intend to buy my Z axis parts from them soon.

Jeremy

[ilya]

I'm looking at the picture at Ahrens site (http://www.cncrouterparts.com/parts.html). Am I right supposing that if I won't be using the drill rod I'll need 2 shaft collars (part 9) instead of 1?
Also, how tight should these collars be clamping the bearing block?

I think that fixed gantry will give me the rigidity I need and will spare me from lot's of headache. However the Y footprint of the machine would be twice as much versus moving gantry. So I kinda haven't firmly decided on this yet.
What I thought is I can use some steel square tubing as a support for an aluminum frame to gain more mass and rigidity. What do you think?
I can't estimate costs yet because 8020 autoquoter doesn't work for some funky reason. I'll upgrade my Autocad and see if it will work...

What kind of router do I need for aluminum machining? I'm going to use K2NC clamps, so I have quite a limited choice.

Need to find more information about motors, drives and the like. I have no clue what power motors need in this application. Ahhh... Back to reading.