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View Full Version : trying to keep the machine close to the cutting area



reefy86
04-12-2017, 01:54 AM
ok so i am bringing my size down from cutting 8x4 sheets to 4x4 due to size issues, i need to try and get the whole machine size as close to 5ft wide as possible but i cant seem to bring it any lower then just over 7ft with the design i have. I am just focusing on cutting wood only now but at very high resolution so if anyone can give me some pointers on how to get this thing smaller while still keeping it very strong would be great.

cheers

23308
23310

magicniner
04-12-2017, 09:59 AM
If your rails were on the underside your ball screws could be on the inside, this could save you significant width as only the vertical moving parts of the gantry would need to be outboard of the working area.

Neale
04-12-2017, 10:31 AM
Here's something a bit more radical. You say you want to cut wood, but that spindle bracket and Z plate assembly looks as if it's designed to carve battleships from the solid. Why not slim down the Z plate so that, below X rail height, it is no wider than the spindle and its mounting. The mounting itself stiffens the Z plate anyway. Put just one hiwin carriage on the bottom Y rail right behind the spindle. Keep, or widen, the top of the Z assembly and use two carriages which can go over the top of the X rails for more resistance to twisting. That could buy you about 100mm extra Y travel, at a guess.

My feeling is that our size machines barely make the hiwin slides break into a sweat - they are happy to take much higher loads than we usually put on them, and one at the bottom might well be sufficient.

Desertboy
04-12-2017, 11:14 AM
I have 1.3m of travel * 80cm of travel in a footprint of 1.6m*1.1m plus the bit my nema 23's stick out but they could be belt driven and slung under the body to save space.

23311

Although I used aluminium extrusion

My Z axis wastes 25cm of travel! Simple redesign could easily save 10cm

reefy86
04-12-2017, 12:48 PM
originally i was making this to also cut acrylic and thin aluminium, i have no idea what is over the top for just doing wood cutting.

Desertboy
04-12-2017, 06:12 PM
originally i was making this to also cut acrylic and thin aluminium, i have no idea what is over the top for just doing wood cutting.

Steel is cheaper than aluminium so if you have the skills go steel every time! I would have built a steel router if I hadn't recovered my aluminium from an old magazine printer I paid 30 for all the aluminium extrusion in my machine otherwise it would have been over 300 from KJN with, the cutting, drilling & T nuts for Hiwin's only was another 100 (Which I had to pay for)

I've also spent a good 50 on A2 stainless steel bolts to assemble mine and I already had probably 1/2 the bolts there's over 200 bolts in my router from M3 (limit switches) to M12 lol it all adds up.

I'll be cutting some Oak on my router next week in the middle of the bed so I'll tell you how she does then lol, but having a stronger machine than mine would mean you can run it faster which is always good.

reefy86
04-12-2017, 06:25 PM
yeah let me know how it goes :)

Neale
04-12-2017, 10:22 PM
My own machine is built from steel. I agree with Desertboy - steel is a really good material. The welding doesn't need to be certified pressure vessel standard - follow some Youtube videos, read, practise, then do it all again. You can weld a structure that is strong enough without too much trouble. Not necessarily pretty, but it doesn't have to be pretty to work. But you do need a MIG welder and an angle grinder.

Strength - a lot of people here will tell you that you need heavy section steel box. They may be right. However, I used 3mm 50x50 and 100x50, and it works fine. Is it strong enough? I made a bit of a mistake this afternoon - I had generated my gcode with the zero reference on the top of the material but set up the machine with zero on top of the spoil board. So I plunged through 1/2" birch ply and a couple of mm of MDF spoil board and cut it at 3000mm/min at that depth with a 6mm carbide cutter in a shower of chips. I don't know what the limits of my machine are yet, but it seems to be stronger than I expected. Can it do fine work? I have repeatability (using a touch plate multiple times) of +-0.003mm, according to the Mach3 DROs. I have machined raised text, about 3-4mm high letters, into a lino-cut block to make a small printing block, using a v-engraving tool and VCarve to generate toolpaths. Came out very well. That's using a steel gantry that weighs around 40kg with spindle, etc.

I'm sure that other people will cut deeper and faster, but if you are doing fine work, you aren't going to be cutting that fast anyway. Don't ask me how my machine handles aluminium - I have only done a very small amount of cutting in that, not enough to judge performance. I would happily, very happily, go with steel again as a building material, though.