Stell frame cnc 1500X1000. Adjustable table your opinion please

[Boyan Silyavski]

Only because I didn't let it cure long enough before tightening it down. I've obviously checked it all again since and It's not moved one bit. If I build another machine I would be using the same stuff again.
silyavski, it was not nearly as bad as you are making out, remember it was others who said it was a 'disaster' not me.

Could you do the 10g-20g mixture test if you have anything left? To see what happens?

[EddyCurrent]

Could you do the 10g-20g mixture test if you have anything left? To see what happens?

How should the test be done ? what are we looking for ?

[Boyan Silyavski]

How should the test be done ? what are we looking for ?

Just mix a very small amount, 20g in total and see if it hardens well. Should use a precision scale though. The idea is that the epoxies if don't behave well in very small quantities but behave well when mixed half kg for example, are poor quality.

[ba99297]

Thank for your answers.
Syliavski also thanks for your intention to help
I will search a little more and if i didnt find anything i will let you know.
My last search bring me up to this company. Have a look at the page that discribes its products

http://www.5m.cz/en/epoxy-resins/

PR 220 (resin) with EM316 (hardener ) has 120-150 minutes pot life
PR 220 (resin) with EM317 (hardener ) has 200-250 minutes pot life !!!! but not curing at room temperature

Here in Greece they import only 315 hardener to be combined with PR220 resin. This hardener suppose to be the fast, but it has pot life 50-60 minutes 200 gr at 25C ( when west system 105+209 has 40-50 minutes 100gr at 22 C). When i ask about the price ( here in Greece ) they told me 22 euros+vat but am not sure if they are talking about the PR220 or PR102 resin. Have a look.

[ba99297]

Hi everybody
Long time has passed since my last post
It is because after summer holidays, schools starts and (as I am a school teacher-computer science) I had too much work.
Last night I decide to restart by installing the hiwin profiled rails
I start with X axis in order to install the master rail. I measure, I mark the holes and then drill with 4mm first and then with 4.2mm in order to tap the m5 bolts.
Then I bolt two carriages on a steel plate st39 ( not perfectly milled yet ) and then I put the carriages on the rail. The movement isn’t very easy. As I put pressure on the plate, the movement become easier ( as cause of preload overcoming). I didn’t lubricate the rail or the carriage for this first test.
I didn’t epoxy level the 80X80 beams (where the rails rest) as when I test them against straight edge I didn’t notice more than 0,15mm gap, so I will go on with shimming.
My questions are

1. Do I have to lubricate the carriages for these first test travels
2. What will be the normal pressure for moving the carriages
3. As I apply force in order to overcome the preload forces I hear a sound from the carriages (krrrrrrrr ) is this normal?

Later I will come with photos and videos to show how the carriages move.

Thanks for your time

Vagelis

[Jonathan]

0.15mm is a pretty huge misalignment for these sorts of rails. The datasheets specify something in the order of micrometers.

1. I would, since if you're having trouble aligning them then you're potentially putting big forces on them, so lubrication might help prevent damage.
2. About the same as before the rail is mounted. When a flanged carriage is bolted down to a flat surface, the carraige is often designed to distort and apply slightly more preload, so you may notice an increase in friction. However if you leave the carraiges off what they mount on for now, there should be no more friction with the rail bolted down. If there is then your rail is seriously bent.
3. No ... sounds like the rail, or something, is bent a lot.

[Boyan Silyavski]

Hi Vagelis,

You will do it right, just don't be in a hurry. It's a precision work.

Use oil not WD40!!!

RTFM!! Download and read the Hiwin Manual. Where the say about the WD40 by the wayNot oiled makes noise but moves freely
I told you need straight edge. Spend 60 eur and buy at least the 1meter one. It would easily show your real misalignment spots.
Don't push anything directly, I mean the bearing blocks. Work around them so everything is straight and so that screws are in the middle of the hole. Where necessary to widen holes.

[vargai]

Hi Vagelis ,
I am happy you are on board again
I do not think you have big preload -Z1?
Fist I think krrr is not critical , lubricant will help to reach prrrrr.:)
I only have an use bearing at home so I am waiting the sound result.
The pushing force is a good feedback I suppose
Regards
István

[ba99297]

It is very possible to go on with epoxy finally as I measure gap (beam against straight edge ) nearly 0,25mm and shimming seams to be very difficult for me.

As i had told here in Greece they import 105 west system epoxy but they don’t import 209 hardener but only 206. So i will make some experiment with other epoxies much more cheaper ( 25 euros / 1,2 kgr). Ebay supplier asks 90pounds for 1.2 kgr 105-209 system.


The problem is that the temperature in my work place is now 16-17 celsious and it is dropping more as Decemper comes. So if i want to apply the epoxy method i will have to make a place with controlled heating system in order to keep the temperature as low as 20-21 celsious.
Second solution will be to go on with shimming and third ( the most expensive ) to ask a friend of mine ( that builds woodcutting machines) to use one of his machines and mill my top beams in order to come in the same plane ( but this will cost).


I want to ask
#1 ( very important to know what I am trying for )
When you measure the flatness of a beam ( or epoxy surface) against a straight edge, what is the acceptable tolerance-gap ( so we assume the surface is straight) . I use light to understand whether my top beams attach the straight edge. The touching points can be easily seen. But at other points althought i can see that there is no touch ( light passes through) , the 0,02mm Gap Filler cant pass through the gap. So what is the critical gap ? the light passing test ( that is less than 0,02mm ) or the 0,02mm gap filler test?

#2
When someone use the solution with the adjustable top beams ( without epoxy) or the shimming method how does he succeed to have the top rails in the same plane. How does he know when the two rails ( left and right ) are in the same plane? Is the thread method accurate ( the method that with the use of two threads you create the diagonals of the top rails like X. If the diagonals are in touch at the centre that means that the rails are in the same plane.

#3
When we use the epoxy method we first drill then tap then close the holes and then apply epoxy or we apply epoxy then drill and tap?

#3
What is the right angle to hold a single beveled straight edge? 90 degrees?45? something else?


Thanks for your time
Vagelis