Was wondering if anyone has seen my last post, been up for 4 days now. I'd like to know if I'm going in the right direction before spending any more time on the drawing?
I notice you've opted for steel plate on the Y and Z axis. The vast majority of people use aluminium instead of steel since it is so much easier to machine, particularly with limited/basic tools. 20mm is a good size for the Z-axis.
You could make the top Y-axis rail longer (820mm ish?) and increase the spacing of the two SBR25 bearings upon it, so the plate the Z-axis bearings are mounted on would be a T-shape. Although not critical since your Z-axis is already a good size, this would increase the rigidity for little extra cost.
What's the plan for the bed?
Hi Jonathan and thank you for your post,
What's the plan for the bed?[/QUOTE]
I am leaving that open in this sketch, but I have plans for several options:
1) A simple MDF bed with 2 layers, support and spoilboard
2) Aluminium (or maybe even steel) drilled and tapped
3) Open to allow a 4th axis to be mounted
4) A removable T Slotted Steel bed across the front cross member
5) Open to allow me to mount motorcycle engine casings on the bench beneath for engraving
Basically I have left it free to see what develops over time.
I'm hoping with the small overall size and the relatively large size of the frame in comparison, it should be up to most of what I can see me throwing at it... Only time will tell.
There's also now 4 bearing spindles readily available - these are 215mm long instead of 200mm.
Thanks for your post,
"I think we're talking on cross purposes..." - Yup my mistook!
I'm going to have to borrow a mates workshop for this build, so I'll be able to work the steel plate almost as easily as the Ally there, so from a rigidity and space point of view I'm plan to stick with Steel plate.
I wasn't aware of the extra row of bearings in the 25mm bearing blocks, that's a good reason to stick with them, the space saving is only 10mm if I went to 20mm rails on the Z Axis anyway.
Here are the latest drawings for the machine, it's nearly there, just need some advice on the X Axis belt drive, or more specifically the idler pulleys, I can work something out, but I'd rather go with a tried and tested system. They are currently set at 25mm OD, their construction and size are open to change.
I know steel rings like a very ringy thing and some form of filling is in order, I'm pretty sure I wont be able to use epoxy and agregate from a weight point of view, I have to consider the stability and balasting of the boat. I was wondering if expanded foam would act as a dampener, anyone got any experience/ideas?
Spindle shown is Chinese W/C - 2.2kW one, I also plan to have a dedicated low speed job for the harder materials. My supply is currently (Sorry for the pun) limited to 16Amps on the landline - going to have to do some sums to see just what a compromise this will cause. 2200W @ 240v = 9.2 Amps so 6.8Amps left. This means I would have not a lot left for everything else (Fridge, Lighting, 2nd PC!) , Me thinks either a 2nd landline or more likely a generator will be required!
I can pm the sketchup file if anyone would like to check it over, all I really need to know is that the design is buildable, I'm fairly sure it is, but sometimes you can miss little details when you are too close to something.
I'd like to learn the capabilities and limitations of this machine design, I've taken a lot on board for this design from previous posts to this log and from reading other peoples experiences, but there has to be a time when you stick a stake in the ground and this is where I find myself. If you see something is dangerous or impossible please tell me so and I will change it. Otherwise this is the machine I plan to build warts and all.
If the design is doable (Not perfect, but doable) I plan to start buying components sometime in the next week or two. The order I think I'm going to use is something like this:
1) Linear Rails and Bearings - Need this to be sure of the holes I need in the steel.
3) Pulleys and belts - to make sure of the sizes so I am safe for the Ballscrew Machining.
4) Ballscrews and Bearings.
6) Electronics & controller software. 3 choices Planet CNC USB, EMC2 or Mach3(4?) Need to do a feature/cost comparison Gut says Planet CNC as I need a BOB and the software was written to work specifically with their BOB, Head says Mach3 as it seems to be the most used and the little perverted Demon on my shoulder says EMC2, as it's about time I learnt about Linux!
7) Spindle - probably use my hand router to start cutting and pay for W/C jobby and the dedicated low speed one.
8) Additional software for modelling - going to start with the free stuff to get the feel of the machine.
Does this seem logical, are there changes I should make?
Another long post, so I'll stop here and wait for a while before adding any more.
Last edited by BikerAfloat; 17-09-2012 at 01:58 PM. Reason: Made stupid mistake about ER16 Collets, when ER20 is what I really need - Doh!
sorry i can't add much again, but what i will say is consider emailing the dude your getting the rails and screws off first for a price and pay outside of ebay, this way you will get a better price and while your at it get him to quote you to include and also not include the spindle.. chances are due to combined postage and a big order you may find yourself getting the spindle alot cheaper than anywhere else.. this is certainly my play when the time comes.
also i only just realised your building this machine to work on a boat.. thats just awesome in its own right.
expanding foam is also something i was considering for my build.. it's very cheap and i think it would go some way to take the ring out of the steel as it wouldnt have any air to resonate through the center of the box section