Let the fun begin !!! ???

[PAULRO]

i had intended to use 20 mm rails on the z axis but after reading the various posts of your good self I am now going to use 15mm rails and guides to suit so i think a redesign is in order.
the rear plate should be shorter alright i just left it long enough to house the motor with a body of 100mm long and a plate to hold it.
i suppose the travel of the z axis could be longer but i went with that travel because of all the discussions about the length of the lever created by the extension. i suppose it's another trade off , keeping it to a minimum while having enough scope to machine to a reasonable depth. i'll get cracking at it again tomorrow, my shutters are starting to descend !

[JAZZCNC]

i had intended to use 20 mm rails on the z axis but after reading the various posts of your good self I am now going to use 15mm rails and guides to suit so i think a redesign is in order.

No I wouldn't. There's very little price difference between 15 & 20 and the bearing size and overall height makes building the z axis easier regards clearence for ballscrew. With 20mm you still need to machine a recess for the ball screw but it doesn't need to be so deep. With 15mm the recess is too deep so you end up having spacer blocks and this makes achieving accurecy that much harder.
In the past I've made Z axis for people who use 25mm rails just to get around having recess or spacer blocks thou I wouldn't take that route personally.

I've got 180mm on my Z axis and I rarely use more than 100mm and often it's much less than 80mm and most of this is for tool clearence not actual cutting depth so don't go chasing length as you'll probably never use it.
The fact you will have adjustable bed means you'll find a balance between Z extension and strength for the type of work your doing. This is the beauty of the movable bed you are very flexible and can always find the best height to suit the job IF NEEDED.!!! . . . I highlight these words becasue in practice you'll rarely move the bed (Because it's a pain in the arse resurfacing) but instead find that balance I've spoken off.
In normal DIY wood working every day use your very unlikely to use tools with over 100mm cutting length so I find 100mm is more than enough on a adjustable bed machine as I can always bring the work to the cutter if needed or create clearence by lowering bed.

[PAULRO]

i had used 20 mm flanged bearing blocks in the original dwg and that impacted on the clearance for the ball screwnut. I had also designed the z axis plate to be machined at 160 mm wide to try and keep the gantry length to the minimum . I should have used 20 mm square type bearing block to give more clearance and accommodate the 160mm width. ya i will stick with the z axis travel of 150mm - 160mm and adjustable bed. good call. i will have to get a supplier organized for the guides and rails. I dealt with chinese suppliers in a previous job and there were reliable so i'll drop them a line and see where it takes me. maybe i should wait until i have secured the rails and guides before I go any further with the z axis design?

[PAULRO]

Has anybody used the linear guides and rails from Chai? i have organised the ball screws from him and thought i would use his linear gear but only on a recommendation from the previous builders here.

[JAZZCNC]

Has anybody used the linear guides and rails from Chai? i have organised the ball screws from him and thought i would use his linear gear but only on a recommendation from the previous builders here.

If your talking about the Profiled linear guides then yes I use them all the time and they are fine.

[PAULRO]

steel has arrived and is cut and both sidewalls are welded.


I have to string the crossbeams and tie both together.

I contacted http://www.ecfibreglasssupplies.co.uk /to purchase epoxy 105 and hardener 209 but drew a blank . apparently they don't stock 209 hardener but told me the 205 or 206 hardener are very similar but for pot time and cure time. has anybody used these hardeners? i'll probably go with the 206 because it has a longer pot life but would like some feed back before i do.

i also spoke to Chai about his linear guides and rails and the preloads are as follows
Z1: 0-0.02C or Z2: 0.02C-0.05C . i'm sure either of these will do the job but would like to know which preload is the preferred choice for wood routers.

[Clive S]

Paul I contacted ecf as that is where I purchased mine from they don't stock it but they can order it, but they will not deliver it out of the country. Here is a chart that will show you the difference between 206 and 209 (page 3) http://www.paynesmarine.com/document...0Adhesives.pdf as far as I can see the 206 cure time is about 9 to 12 hours and the 209 has a cure time of 12-24 hours but the 209 is recommended in hotter conditions. The idea behind the slow cure time is not how long it takes to pour it, as that is only a few minuets but the time it takes to let it level out. ..Clive
.
I have done a bit of research and you can buy it in Dublin here:- Waller & Wickham
Unit 96, Baldoyle Industrial Estate, Dublin, , Republic of Ireland
353 18392330 He will be in his office around lunch time today.

[Jonathan]

Z1: 0-0.02C or Z2: 0.02C-0.05C . i'm sure either of these will do the job but would like to know which preload is the preferred choice for wood routers.

You get a slight increase in stiffness with higher preload, at the expense of lower life and higher driving force. For a wood router the change in stiffness is negligible compared to other parts of the system, so I'd go with Z1.