[jestah]

Hi guys,

Bit of shamless cross posting to try to get a few more replys on my thread as I am keen to cast a desktop mill column and base next week but would really like a few more eyes to my rock selection and machine design before committing to such a big pour!

http://www.cnczone.com/forums/epoxy_..._-_please.html

thanks a ton for having a look!

[yancho]

Hello jestah.Make holes in the forms. Not only lighter but also gives structure and strength.For example, you can install pipes for cables at the base, tower and stand Spindle.This will make it more easily for casting concrete and save.For use steel pads, aluminum is soft.However, the machine is expected to operate for years.Success and good luck, because it is always necessary.Yancho

[stewi]

Hi jestah,

your Z-motor looks a bit too small for my taste since I can't see a counter balance in your design either.

[jestah]

Hello jestah.Make holes in the forms. Not only lighter but also gives structure and strength.For example, you can install pipes for cables at the base, tower and stand Spindle.This will make it more easily for casting concrete and save.For use steel pads, aluminum is soft.However, the machine is expected to operate for years.Success and good luck, because it is always necessary.Yancho

I have added some small holes to run wiring as well as two post tensioning cables but cant help but think a solid block is going to be better for vibration damping than something with a cored centre.

I have to buy 30L of resin so happy to cast two solid blocks as this will use most of it up in one hit, Can any one else confirm that I will have a better product (looking for vibration deadness and weight over trying to save some cost with using less material) by adding a core to this casting.

Aluminium is soft BUT is cheaper for me to have machined post casting and most importantly has a far closer thermal expansion to the cast rock than steel. My fear with steel is that it will start pulling away from the casting over time due to it thermal expansion. Two people have said steel and a few have said aluminium, any one else have an opinion?

Hi jestah,

your Z-motor looks a bit too small for my taste since I can't see a counter balance in your design either.

Each axis has a 960 oz/inch stepper motors that should be enough with a 5mm pitch ballscrew to raise and lower the 40kg or so for the z but they are being used as I have them for a wood router I was originally making. I am putting them on the mill to cut the parts to finish that at which point I plan to swap them onto that and upgrade this rig to servos.

The counterbalance is a good idea, gas struts look popular but would a dead weight, a few pulleys and some wire work better?

[stewi]

Each axis has a 960 oz/inch stepper motors that should be enough with a 5mm pitch ballscrew to raise and lower the 40kg or so for the z but they are being used as I have them for a wood router I was originally making. I am putting them on the mill to cut the parts to finish that at which point I plan to swap them onto that and upgrade this rig to servos.

The counterbalance is a good idea, gas struts look popular but would a dead weight, a few pulleys and some wire work better?

It depends on the speed you want to go. If all motors and spindles are the same, than X and Y have much less to do against Z. Gas struts are only good until they leak. Pulleys should have as large of a diameter as possible. Look for an extra 40kg balance weight.

[Steven.ji]

It looks good Steven. Are those big channels on the front of the machine connected to the troughs on the top? if so, I would suggest running them left to right rather than front to rear. As they are, they would dump chips on the operator's feet...

bob

there's a tank for chips collection

[Steven.ji]

It looks good Steven. Can you write more information about the machine-weight,size.
Thanks ! Yancho.

Weight:800Kg

Size: 850x900x1500

[Steven.ji]

Is that full epoxy granite Steven..?
Is that a machine for yourself as hobby or do you have a company that sells them.?

It's full epxoy granite

we have a company and sell them

[Steven.ji]

Nice work! Looks like you copied the gantry design from that nice German (Dutch?) machine we talked about earlier.

I never copy anyone

which German machine your talked about earlier?

[RomanLini]

Hi Steven.ji, sorry I was not accusing you of doing something wrong, but your gantry does look a lot like the German one by Thomas Zeitz, his machine is called FS2MG we talked about it in this EG thread, post #4059 around there.

His build log;
http://www.cncecke.de/forum/showthre...ght=andre+finn
http://www.ktm-reiseenduro.de/tz/menue.htm
To get to the photos of the FS2MG on his web page you navigate;
(top menu) Maschinen -> (then left column) Neu im programm


http://forums.anandtech.com/showthread.php?t=2022096

Looks like he's got a new model there too (FS3MG);


Anyway Steven.ji your machine looks very nice!

[stewi]

[QUOTE=
Each axis has a 960 oz/inch stepper motors that should be enough with a 5mm pitch ballscrew to raise and lower the 40kg or so for the z
The counterbalance is a good idea, gas struts look popular but would a dead weight, a few pulleys and some wire work better?[/QUOTE]

If your spindle has a diameter of 15 mm, than the 5 mm pitch would convert the load of 40 kg to a torque of 0.0527 kgf*m or 73.18 ozf*inch. The ball screw has likely an efficiency of 60%, which cranks up the required motor torque to 121 ozf*inch.
Even at low speed the motor only exerts the pull-in pull-out torque. When the full step is completed, we see something like the holding torque. Assuming we get only 30% of the holding torque, we are already at 406 ozf*inch. This is all without friction and at low speed of ~ 200 pulses or 1 rev per second. At 400 pulses per second, torque drops by another 30%. Go 600 pulses and the motor will only vibrate.

[yancho]

Coefficients of Linear Expansion
Look here the smaller number is less linear expansion.About your proposed steel.Success yancho

[Steven.ji]

We produced a smallest machine base for engraving of 50Kg

[yancho]

hello Steven.I wanted and working dimensions of the machine (what moves the axes). What use spindle?I have one more question-concrete for epoxy resin using a resin or unsaturated?Many thanks Yancho

[Steven.ji]

hello Steven.I wanted and working dimensions of the machine (what moves the axes). What use spindle?I have one more question-concrete for epoxy resin using a resin or unsaturated?Many thanks Yancho

XYZ 400x400x150

spindle diameter is less than 85mm

[Steven.ji]

hello Steven.I wanted and working dimensions of the machine (what moves the axes). What use spindle?I have one more question-concrete for epoxy resin using a resin or unsaturated?Many thanks Yancho

epoxy resin

[yancho]

Thanks Steven.Yancho

[jestah]

Coefficients of Linear Expansion
Look here the smaller number is less linear expansion.About your proposed steel.Success yancho

Hi Yancho,

Thanks for posting that data, I was going of the info in the index thread that states

E/G and aluminum match well thermal expansion wise and good for embedment of 80/20 etc.<A href="http://www.cnczone.com/forums/showthread.php?p=246652?postnum=113"> Link to Post113</A>

but as I can see from your data that steel is a better option. thanks for the heads up and guess I should get out to a steel yard asap

thanks
jestah

[yancho]

Hello jestah.I also want to make such a machine-CNC.I have a master degree machine tools and 20 years of the conventional work.I think that concrete is best, because when the foundation for the rails and aligned them correctly, avoiding costly and heavy machining.Not so fast, consider it well, once the mold is made.Of course you can always improve it.Ask for me will be happy to help.I use Solidworks 2008/2011.Yancho

[jestah]

Hello jestah.I also want to make such a machine-CNC.I have a master degree machine tools and 20 years of the conventional work.I think that concrete is best, because when the foundation for the rails and aligned them correctly, avoiding costly and heavy machining.Not so fast, consider it well, once the mold is made.Of course you can always improve it.Ask for me will be happy to help.I use Solidworks 2008/2011.Yancho

Thank you so much for you help, to be honest I am only 25 and have no formal training. I have spent 3 years reading different posts on the zone and based my design around my finding and often feel unsure if I have a good design as I have never worked with metals before.

a few post back the German machine looks like a far better solution as well as being easy for me to cast so I am now rethinking my ideas and considering building something very much like the first smaller blue machine.