RE: driving the long axis with 2 motors. You don't have to with R&P!
All I did was to make a shaft with a pinion on both ends and a drive pulley inboard of one of them. Then simply mount the motor in line with the pulley and you are driving both sides of the gantry with 1 motor, no crabbing, simples.
If you want to get fancy you can use a zero backlash pinion on one end but I didn't think it needed on a router.
Jeff.Nothing is foolproof......to a sufficiently talented fool!
The principle is the same if using screw or rack.
drive it from both sides and you won’t have a problem.Visit Us: www.zappautomation.com
End of the day this is a router and R&P will give Julie all the accuracy she needs whether she is carving long panels or cutting parts for furniture. All I would suggest is she drives both sides with a SINGLE motor (bought from Zzap).
Jeff.Nothing is foolproof......to a sufficiently talented fool!
03-10-2009 #14Visit Us: www.zappautomation.com
Thanks for all the replies so far. I haven't disappeared as fast as I came, just been doing a lot of reading and research.
This immediateley throws up a load more questions. I hope others will excuse a few really basic ones. For starters:
1. I originally suggested wood / MDF construction, but having seen the construction methods others have used and investigated various suppliers of extruded aluminium profiles, that seems a much better way to go. I have so far come across a number of such suppliers, having downloaded the Valuframe catalogue and checked out the Rhonmac (same system as Valuframe?) and Marchant Dice websites. I've also seen references to Bosch. Is there anything significant to choose between these, or other, systems / suppliers?
2. I've read through all the posts concerning HiltonSteve's very impressive build. If I've understood it correctly, Steve, you've used just one guide rail each side on the x-axis (but 2 for y- and z-axes). Your gantry appears to have additional rigidity through the Al plate that connects each side beneath the bed. At the sort of size table I'm considering (around 8' x 4') I'm expecting to need to use at least 3 legs per side (I envisage it being free-standing, not bench mounted) and, very possibly, at least one under the centre. These additional (non-corner) legs would preclude an under-bed connection between the gantry sides. I'm presuming I would need 2 guide rails per side for the x-axis and 2 for each of y- and z-.
3. Again with reference to Steve's build, the entire gantry / y-axis structure seems very solid with 15 / 20 mm Al plate throughout. Does it really need this for sufficient rigidity? I imagine I will have a greater need for care here with a 4ft + y-axis, but was hoping that the use of extruded profile with, perhaps, rather thinner Al sheet skinning would suffice. Am I kidding myself?
I will shortly be exiled from the internet for a couple of weeks, so won't be replying again for a while, but this will give me some quiet time for further planning.
The cheapest way to rigid is steel box section, but after making the frame you want to make your fittings adjustable because it won't be quite as straight as you require.
If you want long lengths of aluminium bar or box section, I suggest you stray outside the hobby market and go directly to a stock holder such as http://www.parkersteel.co.uk
Thanks for the reply. I understand the reasoning for using steel, but my problem would be fixing it all together. I'm not into welding at all. Also, if I do go ahead with this, then I'm seriously contemplating installing it in the loft above my workshop and garage. The garage itself would be the only alternative as the workshop is already full! The garage would not be ideal as the floor is rough concrete with a gentle drainage slope towards the door. Besides, my supposed double garage is already almost full with wood store, racking for off-cuts / work in progress, workshop overspill etc. (Well, you know the way it goes. Nothing wrong with my workshop that doubling its size wouldn't put right!)
Assuming it goes in the loft, it will have to be assembled in situ due to access and, should I ever want to move it, it will have to be taken apart.
I accept what you say about leaving scope for adjustments.
Yes it may be over the top and I may have got away with 10 and 15mm plate but it would have made my design more difficult to put together. The cost difference of using thicker material outweighed any potential build problems I may have encountered and also guaranteed a good solid machine. Also I thought about how I could manufacture the parts and what machinery I had available to use, John S did the side plate profiling for me on his beaver CNC then I machined all the rectangular plates one Saturday morning on my mate's bridgeport, then drilled and tapped everything in the afternoon at home, so most of the main structure was made in a day!
The way I did it made sense to me because it was quick and easy to build because of what machinery I had available to make the parts, not everyone has these resources available so you have to do things differently. If I had a CNC mill to play with for a day to make my bits then I would have done things a lot differently!
Last edited by HiltonSteve; 12-10-2009 at 09:15 PM.
Steel bolts together okay, but how are you equipped for drilling holes?
If space is at a premium, a low profile machine could have one long axis hinged to a wall so you can fold it up out of the way when not required.
A bit caravanesque perhaps :heehee:
Thanks for the extra detail. That all makes sense.
Have a heart!! I'm not into metalwork. My interest is very definitely woodworking. Hence, my desire for a large woodworking sized machine. In just one week I've gone from thinking in terms of wood / MDF for this build to conceeding that aluminium would be better. Now you want me to jump straight to steel. You'll want blood next.:sad:
A fold up solution wouldn't help me. My workshop is around 5.5m square, which isn't bad for a hobby workshop, but it's absolutely full. All my main machines, including 800kg of table saw / spindle moulder, are on various forms of wheels or castors so that I can pull out the particular one I need at any one time. There's just not sufficient wall or floor space available without discarding things that are already there.
You ask how I would drill holes. Therein might lie another problem! Before I got quite so seriously into developing a workshop, I bought a Shopsmith combination woodworking machine. I've subsequently replaced most of its functions with much more capable separate machines, but still use the Shopsmith as a vertical drill. In that regard, it's seemed adequate for my purposes to date without going to the expense of a dedicated pillar drill. It has a reasonable sized table to which I can attach a fence, and depth setting ability. Other than hand-held drills, that's my lot for drilling at present. Although I say I'm not into metalworking (beyond drilling and tapping the occasional hole), I can see that some limited capability here could have uses from time-to-time. To that end I've started giving a bit of thought to getting a milling machine. Don't know much about them, so guidance would be welcome. So far I haven't got beyond the Axminster catalogue. In there, the possibilities that have caught my eye include the SIEG U2 and Axminster RF40. Anyone have any experience of these machines by any chance? (Perhaps I shouldn't admit on a CNC forum that I'm contemplating a manual solution here! Perhaps a retrofit one day in the future might be on.)
My table saw can take an aluminium cutting blade claimed to be able to cut up to 30mm, which should be more than adequate for basic straight line cutting to size. (If it can cut 30mm solid, I guess it would be OK on 40mm extruded profile sections. With a 300mmblade, depth of cut isn't the issue and with a 5.5hp motor, I guess it would have adequate power.) That would still leave detail shaping and drilling, of course. Obviously, trying to cut steel would be another matter altogether and not something I'm equipped to deal with at all at present (beyond a hacksaw!).
All-in-all, while I hear you, I still think aluminium, whether extruded profile sections or not-too-thick solid, is better suited to my needs and capabilities.