4' x 4' x 8" Router Build

[Kitwn]

I haven’t looked at the data sheet for the sensor but. I’d assumed that it would be triggered 2 or 3mm before contact and I could then have the hard stop almost flush with the sensor z. How much overrun should I allow for? I guess when it’s travelling at speed something like 5-10mm would be better?


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You need about the same length as a piece of string! All depends on the weight of the gantry, your approach speed for homing (crashes at rapid speed will hopefully be avoided by soft limits once the machine is homed which is the first thing you will do after switching it on) and some stuff to do with drivers that other regulars will understand better than me.

Your Z and other axis (it's Y on my machine but X on many) sensors are right. In practice the overlap of the sensor and your target will not be very much when it triggers. I put slots in the mountings of my targets to make things adjustable but this does increase the risk of something moving and messing up the repeatability of homing.

Kit

[JAZZCNC]

I haven’t looked at the data sheet for the sensor but. I’d assumed that it would be triggered 2 or 3mm before contact and I could then have the hard stop almost flush with the sensor z. How much overrun should I allow for? I guess when it’s travelling at speed something like 5-10mm would be better?


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The distance is determined by the sensor spec, if using just for homes then 2-3mm won't be a problem but if using for limits then usually you will be traveling at fairly high velocity when tripped so the inertia will easily travel 1-2mm if at high feeds.
Also, the accuracy and sensitivity are affected by distance, so it's best to keep the distance on the smaller side of the sensor spec. This way it will react faster but obviously if end on you have less room to stop. 90deg is a much safer setup.

[JonnyFive]

That’s a fair point, I’ll look at moving them through 90 degrees. Thanks!


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[JonnyFive]

Finally got around to sorting the proximity sensor bracket:



I think I'm finally there with the design, still need to finalise the motor choice and sort out some sort of levelling feet - can't decide whether to add levelling casters, they're pretty expensive but probably worth the money if I ever need to move the machine. At the minute I've just got M12 nuts welded on to the base of each leg - they look a little small to me but it seems M12 feet are good for 1000kg each - should be enough!

[routercnc]

I made some steel discs as targets for mine as the sensor will be more sensitive than on aluminium, but both will work.

[JonnyFive]

Just been pricing up the steel to make my frame, the price has gone through the roof!! Almost double what it was when I last looked!! Ouch!

[JAZZCNC]

Just been pricing up the steel to make my frame, the price has gone through the roof!! Almost double what it was when I last looked!! Ouch!

Tell me about it, and it doesn't just stop at the steel, aluminium has also gone crazy. The price of steel is also driving up the price of motors, ball screws and anything else made with steel. Then on top of this shipping costs have gone crazy.

[JonnyFive]

Tell me about it, and it doesn't just stop at the steel, aluminium has also gone crazy. The price of steel is also driving up the price of motors, ball screws and anything else made with steel. Then on top of this shipping costs have gone crazy.

Jazz - do you have a feel for how much things have increased overall? Has everything doubled? Just trying to estimate how much extra I need to find.

[JAZZCNC]

Jazz - do you have a feel for how much things have increased overall? Has everything doubled? Just trying to estimate how much extra I need to find.

Oh Yes, I certainly have a feel for it, every month I feel like I've been Butt F^@£ by one supplier or another. Steel has indeed doubled at least and Aluminium tripled for some grades.

This isn't just in the UK either, Even China and Asia are struggling with the rising material cost's. I have never had a Chinese or Taiwanese suppliers apologise because they are increasing prices and in the last 3 weeks I've had 4 suppliers all say the same thing.

On top of this, the cost of shipping has gone crazy, container prices used to be around £2000, now they are anywhere between £10,000 to £12,000 and taking longer to arrive IF you can get them on a ship.!

Airfreight you need to sell a kidney if it weighs more than a mouse. I've just paid £560 to fly 2 ATC Spindles over that would have cost £120 before Covid started, Why when planes are sat on the ground with no passengers.?

I used to fly most of my stuff over a few machines worth at a time, Now I'm shipping by sea freight 20 or 30 machines worth at a time and motors etc by the 100's just so I can keep continuity and be sure prices are kept sensible. The downside being I'm weeks and months behind waiting for stuff to arrive and I'm paying more for the privilege.!

It's the same with Steel and aluminium, I used to buy steel box section 5 or 6 lengths at a time, enough for a couple of machines. Now the only way I can get sensible prices is to buy 30 lengths. Sheet steel is even worse, I'm paying the same now for 3mm as I paid for 10mm 6 months ago.

I would allow at least 40% extra to what you probably think was going to cost.
If you are serious about building then I wouldn't wait for prices to come down either because I don't think it's going to happen any time soon and it's still going up with no sign of coming down.

[JonnyFive]

If you are serious about building then I wouldn't wait for prices to come down either because I don't think it's going to happen any time soon and it's still going up with no sign of coming down.

I was thinking the same, I could be waiting for years for prices to come down, best to just crack on and suck it up.