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Designing new Router called Maximus
Hi All- I'm about to embark on designing and building a new router. I thought I'd record its progress here. I've had two starts at it but have been interrupted. I decided to start clean sheet as some issues with two of my other routers have highlighted some of the long term wear issues with some components. So I've rethought a few things:
So the rules of engagement: 1) target working envelope is 2400x700x300. I'd like to make it a full sheet machine but where it will live will not have the width. 2) Must be simple. All of my machines have been very simple and reliable as I have put the time into reviews and contemplation and full 3D modelling. 3) This one must cut aluminium as I want to make some parts for the next machine. The next machine will be a 5 axis router and I want to make the machine head. I'm tempted to make it a mill with a sliding table design but I have some long hydrofoils to make and I need a 2400mm plus cut capacity. 4) I have researched rack and pinion (plain and helix) but have not found an economical source for these yet so my current thought is to use 25mm wide AT belt. Very stiff. 5) I usually start designing the bench or base and work towards the tool. This time I'm going to start at the tool and work towards the bench. The Z axis is very important for cutting accuracy and I find I eventually compromise some of the geometry by starting at the base. This is because its like a pyramid and you run out of geometry as you get to the top. So by starting at the top I may end up with a bigger pyramid then I thought but at least it will be very solid. 6) I usually use routers but it's time to graduate to a spindle. So I'll do some more research on that. 7) I have to decide whether to use 15mm rail or 20mm rail. I usually use 20mm but the cost has gone up. Waiting on more quotes from local OZ suppliers. This has made me look for an asian supplier. Anyone know of a good one? I've used PMI, STAF and now WON brands.8) I've attached the napkin sketch of the Z axis and will get this into CAD asap. I use Alibre for this sort of mechanical design. I also use Strand7 and simsolid for FEA analysis of various bits. This helps in deciding which way to go if I have two designs. The stiffer one wins. 9) I usually use stationary motors on the y axis vs having a moving motor design. This is to lessen the weight of the gantry, make the wiring slightly easier as the motors are stationary and it also removes one idler. Idlers are expensive by the time I get them bored and buy bearings. The downside is that the belt run is twice as long so its half as stiff. To counter this I intend to put a motor at each end of the run. The stepper is nearly the same cost as the idler and this will increase the belt stiffness as it will be pulled and pushed along the drive side of the belt. I've had a play with this and it seems to work. I wire the two motors in parallel and drive them from the same driver. 10) Most parts will be laser cut stainless steel or aluminium as is Brevis and Scoot my other machines. Powder coat works out more expensive due to the extra handling involved. Plus I've had trouble with thick powdercoat making assembly difficult. 11) I'd like to get something metal 3D printed so will look at these parts for an opportunity or I'd like to make some of the parts in carbon fibre so will look at that as well. I made Scoot to make moulds and I've only done one mould in 2 years of use!!
That's about it for now, when I get the Z axis modelled I'll put it up here for comment. Cheers Peter S
Re: Designing new Router called Maximus
Re: Designing new Router called Maximus
I will be watching with interest Peter.
Re: Designing new Router called Maximus
Hello GER21 - thanks for the BTS address. Prices look good. My usual supplier stopped stocking the economy bearings and the price then doubled! Which in a kit like Brevis 25% the cost of the kit is the bearings. The price hike then makes it a hard to sell kit. May as well be a bigger machine as everything else is still the same cost. But onward and upward to Maximus... Thanks All
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Re: Designing new Router called Maximus
Started getting into the Z Axis. The aim is to minimise the stack height of the Z Axis linear bearings and the Gantry Bearings. These stacks add up really quick and then the gantry has to be cranked to get the spindle near the forward bearing. Or you accept a big overhang in the structure. I saw a tool plate like this on this forum somewhere and it's the inspiration for the Max redesign.
So the tool plate is like corrugated iron, uses a thinner 5mm sheet to mimic a thick sheet and allows the tool to sit in a recess closer to the bearings. All of this reduces the stack. I usually use 20mm linears but again to reduce the stack it's going to be 15mm this time. The calc sheet shows that the tool plate is equivalent in stiffness to a 17.8mm thick plate which is good enough for the moment. Haven't decided whether it's aluminium or steel yet. It's also 38% the weight of the solid plate so we are well ahead here as well. I have to model the spindle and its clamp to ensure it tucks into the current space. The conventional drive is down the middle of the bearings. Obviously no go in this design. We shall see where this takes us as it develops. I usually try for the smallest elements but this time big will be beautiful...
The 15mm bearings have a static capacity of 1650kgf and a moment capacity of 0.115kNm while the 20mm is 2436kgf and 0.221kNm. In round figures the 15mm are half the strength. But the figures stack up, won't be putting anywhere near the static loads on them. So it will come down to the moments. Will calculate these when we have more geometry to work with.
I've also attached an image of MaxNo1 but this is being thrown out as early designs seem to go... Peter
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Re: Designing new Router called Maximus
I'm torn betwixt a high rail design and a gantry on columns. This machine will be long and thinish. I want to do full length plywood sheets but don't quite have the room to do a full sheet width machine at the moment. The high rail design will mean I have to lean over the rails to do a lot of the stuff I do which would be a pain. But the high rail design is stiffer and this machine is also aimed at aluminium. I want at least 250mm Z as this is what my current router called Scoot has. See the photo of Scoot cutting a rudder for a boat, hence I need a longer router! Been handy with waste boards, fixtures and vacuum clamps taking up Z space. So I think I progress the Z Axis to 90% and the gantry to 90% then decide. Peter
Re: Designing new Router called Maximus
FWIW if I were going to do a machine ground up, it'd be a "high rail" style. So much more opportunity to stiffen up the gantry. As far as I can see the only real downside is fitting in oversized stock but, when you consider the more standard moving tower gantry alternative, you're not fitting overhangs in there anyway.
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Re: Designing new Router called Maximus
If I was doing all long stuff the high rail is the winner. But I do a lot of small stuff as well. Where the machine is going to go would make end access awkward. I think it's pointing at having two machines! I'm building a big shed at the moment and that's the right way to go once I have space. The big shed is so I can build big machines. I'd like to go to a 4or5m long 3m wide 2m high 5 axis machine for car panel moulds and yacht parts. The small machines are sort of learner machines for the biggies to come. Peter
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Re: Designing new Router called Maximus
OK first snag with the Z Axis tool plate - Its fine for narrow spindles and routers but for a big spindle the "gutter" will have to be wider. Most spindle clamps are designed to bolt to the vertical tool plate surface. This design has the end plate in the way even for the small router modelled. So the gutter needs to be wider to take a big spindle clamp. I'll have to survey the clamps to see what sizes they are... I've modelled an Ozito spindle and a clamp that I have for one of the Brevis machines here. It fits, but this machine will take a big spindle so I've got to figure those out. Peter
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Re: Designing new Router called Maximus
So I've had a look and I think 100mm land between the humps may do it. Anyone have thoughts out there? Is 100mm (4") enough for std spindle clamps? So the beauty of the the thick tool plate is you can put a clamp or mount anywhere on it. Peter
edit: better be 120mm wide
Re: Designing new Router called Maximus
Quote:
Originally Posted by
peteeng
So I've had a look and I think 100mm land between the humps may do it. Anyone have thoughts out there? Is 100mm (4") enough for std spindle clamps? So the beauty of the the thick tool plate is you can put a clamp or mount anywhere on it. Peter
edit: better be 120mm wide
Are you going to fabricate the corrugated section or can you purchse it?
Interesting idea.
Thought about fabricating a 'stepped plate'.....hard to explain what I mean. 'top hat" shape?.....lol
Maybe a corrugated section would be alot stronger?