Thread: New Aussie Build

Just one last question...

What do people think about rail size. Going with rods suggestion i am going to use lsk20 on the gantry incase i upgrade to a proper spindle or if i decide to use a beefy 1500w router with 1/2' collet.

Anyway, what do people think about the main axis. Should i use lsk25 or lsk20. I just dont want to use the beefy rails if there is no real reason to. Either way im really looking forward to ordering the rails this week and starting the build. Hardest thing so far is trying to find a place to get the channel surfaced since people here charge sydney rates. Wish i had a mill like alot of you gusy out there. That would save so much time and money.

Daniel

Originally Posted by twistedfuse

Just one last question...

...or if i decide to use a beefy 1500w router with 1/2' collet.

Daniel

Daniel,

Good luck with the build. Looks like a lot of fun. Just a comment about the size of router - one thing I came across in my build was that the weight of the Die Grinder and the Z assembly causes it to drop to the bed when the stepper motors are turned off. I always have to be careful with this especially if I have a very fine bit (0.4mm) attached. This would be quite a lot heavier with a bigger router - I am not sure how the others have got around this. Maybe my Z is too free and would benefit from a tightening up. Just a thought.

Hi Daniel,
Design looks good. Think about a gap between the table and sides so you can cross clamp your jobs. Another great idea from our resident chippie. The way I use my machine the T slots are of no bebefit as I always use a spoilboard under my jobs thus the T slots are covered. Same with a vacuum table if you want to go that way. Not saying the T slots are a waste of time though.

Having seen Greolt's machine operating there is no problem with R&P. The spring loading keep the gear mesh tight enough that there is no backlash.

Machining steel can produce some unexpected results. The machining process relieves the internal tension in the steel and you may find machining the top edge will bow the channel along it's length. Maching a 2m length requires a large machine so explore other options. I think a fellow on the Mechmate forum made a surfacing grinder from a disk grinder so you might want to hunt for that. Alternative might be to shim your rails along their length. Make up an MDF template and use feeler gauges to work out the high spot and then shim the rest of the rail to this height. Another option is to use exopy to create a new bed to lay the rails on. Just floating some ideas and if others know of a better way then chime in.

Hi Jason,
You might find with stonger steppers (internal magnets) that the Z axis will stay put. I have 269oz on mine and there is no problem. If I disconnect the motor it will unwind.

Thanks for the replies so far. Jason, thanks for the heads up on the router. I agree with rod, mine is a 300oz/in motor and my z stays up but in the case of the heavier router i could always add an extra spring or gas strut to counterbalance the weight. I think at most this build will have a die grinder or proper spindle as i want to be able to machine as close to the edge of a full 1.2m.

Rod, thanks very much for the help. I guess i will have to explore my options for getting the rails flat. I know i have a whole heap of aluminum powder around so maybe it is worth while doing a metal epoxy, how well does this stick to the rails? In regards tot he sides having a gap it is a really good idea. Maybe ill make the sides removable to allow me to do this. The reason for the T-Slots is to make sure i can support small pieces still. I guess when i build a vacuum table it would get rid of that need. Either way the other option for later is to allow the full surface to be removed to reveal a water/coolant table for the use of a plasma cutter if i ever decide i need to do some small work for myself but i doubt i will need to do that but i also gives me the option to allow me to use coolant for metal cutting etc.

Another thing which cannot be seen in the picture (mainly because it has not been drawn yet, is that there will be a small section near the bottom end that will be about 2" wide along the front which will enable me to hold some wood vertical so i can machine the ends of stuff, or if i want to do dovetail joints or similar.

I will be looking at buying the channel and steel to make the bottom half of the gantry very soon, and as soon as i get my tax back the rails will be ordered. R&P Will be bought soon along with the timing belts and pulleys.

I guess the first job tonight is to get a photo of everything im selling and finish drawing up the design.

Daniel
P.S Btw, rehashing the Y axis. Which would be better. Using 4 blocks on some lsk15 or using 2 blocks on the lsk20. Sorta limited by the price atm, but either way im happy, i guess i could always order more bearings later if i needed it for the gantry.

Hi Daniel,
You do not want the rails stuck to the epoxy as all you are doing is creating a flat bed.

Originally Posted by twistedfuse

Which would be better. Using 4 blocks on some lsk15 or using 2 blocks on the lsk20.
.

Are we talking THK type rails or round shafting? If THK type then 15mm will support a Mack truck. Plenty big enough for a gantry. Their strength comes from how well they are mounted and spread.

Use 4 blocks or possibly 3. You are going to the expense of using proper bearings, don't undo it by going 2.

If I remember correctly you have some large linear bearings left over from the previous build. Consider using one large rail and two blocks for the Z axis.

I know this seems to contradict my first sentence but in the case of the Z axis and the size of those rails (30mm as I remember them) it can work very well. I have seen this setup on a few machines.

Greg

Rod,

Not sure what you mean by stuck to the rails. I was thinking along the lines of the madvac cnc machine where he leveled the tubes for his linear rails using al. powder and epoxy then filing it back to flat. Maybe i missed something or all the logic troubleshooting im doing at work has fried my brain. Either way i would prefer to do something less tedious and something i feel is more solid rather than a fear of it all cracking off with the vibrations.

Daniel

Greg,

Im talking the THK style linear rails. My thinking was the fact that i thought the lsk15 with 4 bearings would be stronger than lsk20 with 2 bearings as it would reduce chatter/vibrations. Rod was right in saying that the lsk20 are better but now i will leave it as lsk15 profile rails. Im still contemplating using 20mm profile rails instead of the 25mm ones but i think for the main axis, the beefier the better i guess.

Your memory is pretty sharp too. I do have some 300mm long 35mm linear rails. I had looked at the 25mm ones i have at home for the z but hadn't thought about the others. I will probably just use an actuator to speed things up and then change it over after i build it.

Thanks for the suggestions.
Daniel

Daniel

I used 20mm rails on top of the channel iron for X axis. I am convinced they are more than adequate.

Last year I attended the big engineering/automation show here in Melbourne. This year it was in Sydney.

Spent my time going around looking at all the big routers, plasma cutters, water jets and lasers. All but one of them had R&P drives and all but the very biggest had 25mm max sized rails with most having 20mm.

These rails are way over spec'd for how we use them. One rail on it's own with say a weight attached on a 300mm arm is working fairly hard but when you have two well
mounted rails spread say 900mm with a a rigid structure (gantry) coupled across them the bearings in that situation become enormously strong.

They must be seen in the light of the overall structure. All my opinion of course.

Greg

Greg,

I was extremely fortunate this year as i actuall got to go to the Manufacturing expo in sydney. Sawmany amazing machines bu since i was there for work i wasn't able to take as much in. AT the time too i was concentraing on small routers so didnt take overly as much notes on the large. I am like you, im sure thy were 20mm rails or 25mm rails. Since they are completely supported. i would think that i should look at 20mm but since i would liek to do some aluminum stuff i was thinking 25 which is where my problem (indicisiveness). lol. Maybe ill save a few pennies and go for the 15 and 20mm set but still not sure. Its one of those things, you and rod both have great points. Just one of those things to think about.

Daniel
P.S I was just thinking about the rails. At the expo alot of the machines have rails mounted on vertical surfaces, hence why they would need beefier rails. Well thats my thoughts anyway.

Greg,

I forgot to ask. Where did you get your timing belts and pulleys from, what about your R&P? I got a quote from a company in Perth but for the pulleys and belts, and got a quote from TEA for the R&P. Doing the rounds to see the price differences.

Daniel

Got belts and pulleys from here,

http://www.piesau.com.au/

I used T5 but should have used AT5

R&P from TEA. Module1

Greg

Thanks greg,

Will give them a shot. I'd have to say the price of the R&P from TEA isn't too bad. Will have to start ordering very soon. Steel should be organised very soon. I guess ill have to figure out the paint scheme sooon and get some metal primer and pint. lol.

Daniel
P.S Just curious too, the R&P did you get the stainless steel or just basic steel rack?

This is just an update on the chevy logo. I did this on aluminum with the wood v bit from AP workshop. I think that changing the bit out for a proper d-shape engraving cutter or quarter round cutter will give alot better results.

I think i have a little rework to do, but its defintely gettingt here.

Daniel