1 other note! I lost my tight wire edge as I had to sand so much. Oh well, I have another way to get an edge with a tight wire for mounting the rail.
Andrew
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1 other note! I lost my tight wire edge as I had to sand so much. Oh well, I have another way to get an edge with a tight wire for mounting the rail.
Andrew
Good to hear that you could recover this. What would be the maximum and minimum epoxy thicknesses?
Less than 1/16" thick at this point. I did notice I do have more work to do as there is some crowning in my sanding job from the inside to outside edges. I will work on it some more with the granite parallel to remove it.
After that, the next issue will be to match the second rail to it.
Andrew
You might also consider potting the rail in place. Make pads over the screw holes and align your rail by adjusting those (you probably want some horizontal alignment pads too). Once everything is in spec and tightened down, dam it up and fill in the gaps with epoxy.
That is similar to one of the techniques described here:
http://www.moglice.com/handbookpdfs/handbook.pdf
This thread goes through a lengthy thought process on this subject: http://www.cnczone.com/forums/linear...ear_rails.html
This is a great guide on mounting rails: https://tech.thk.com/en/products/pdf/en_b01_089.pdf
bob
Crowning fixed. I'm getting close. Time to pour the second rail.
Andrew
Well acetone certainly thinned the epoxy but it created a bigger problem. The mixure within a few minutes dissolved the double sided tape I was using to hold my dams in place. As you can guess I have a mess as most of it has now leaked onto the floor. YUK! I did my best to plug up the big hole and will re-pour after this round has cured and plugged up the holes.
Andrew
I have been watching your progress with interest since we are about the same place as you are on our steel table build (will post a build log soon). Similar to you I am using 2x2 square tube for most of the frame and 2x6 rectangular tube for the long (X) axis (table is 10' in X and 5.5' in Y). All of my material is 11 guage (almost 1/8" thick) as I chose to use inserts for all of the threads instead of tapping a million holes. I have all along been planning on using an epoxy leveling compound to account for the natural bow of the steel and was a little dismayed when your pour went south on you. I contacted West Systems and explained what I was planning to do and the recommendation was to use the 209 hardener instead of the 206. As of today we have poured both X rails and the results look very good. The 209 has a pot life of up to 50 minutes, thin film cure of 3 - 4 hours. I am thinking it will need 3 - 4 days to cure completely. With the 209 hardener the resin flowed nicely and seems to have leveled the rail as I had hoped. One of the rails is at about 30 hours, the other was poured last night, about 14 hours ago. The surface of the epoxy on both rails look like glass.
Thanks for your build log, I'll keep watching to see what other 'pearls' I can pick up from you. A couple of pictures below:
jsmith,
I too am planning a build similar to this. If/when you start a log, please post back here and let us know. I'd like to see it. :)
How much did the epoxy and 209 hardener cost? Whom did you buy it from?
Thanks.
/Not a hijack.
I had a difference of ~1/8 - 3/16" in the steel from the high to the low, but when I poured I wanted to have a continuous shim the entire length of the X rail. The minimum thickness of the shim is on the order of 1/16 - 1/8", the maximum thickness should be about 1/4" (won't be able to measure until the cure is complete). I ended up using about 20 oz for each side (each rail), so 1 qt of 105 resin and 10.5 oz of 209 hardener (the 209 hardener is mixed 3:1 with the resin unlike the 206 which is mixed 5:1). I got the resin and hardener at West Marine, and you might want to sit down, the quart kit was just shy of $75.Quote:
Originally Posted by amishx64
I will be starting the build log very soon, I am getting a lot of heat from the #2 son (who is doing most of the work), guess he wants to be famous ...
Thanks for the info. Very helpful.
:eek:Quote:
Originally Posted by j.smith
That's no good. Think I could get away with just bolting the thing down to the steel and just getting a machinist's shim set? Also, do you have to sand down the epoxy after?
It's good to hear that the kid is going to help you out. I mean, some one has to keep you in line and on task. ;)
First off, I will not be using rails like the_canuck is, I will be using the extended linear carriages from CNC Router Parts to support the gantry, so I will be mounting a 1/4" x 3" piece of steel on top of the X rails.Quote:
Originally Posted by amishx64
I thought about shimming at each of the bolt locations but was sure it would take a lot of time and did not believe it would be as good support as the continuous epoxy 'shim'. Setting up for pouring the epoxy was pretty straight forward and then gravity did all of the hard work. I am estimating that my gantry will be in the 150 lb range so I decided that I did not want to have unsupported sections between the bolt locations. Knowing what I do now, if I do this again I might go with thicker material for the X rails, it sounds like the deviation in the_canucks material is much less than mine. The 11 ga 2x2 square tube is very true but the 11 ga 2x6 rectangle has a pretty good bow in it from end to end, could be a remnant of the way it was handled, both 12' lengths that I started with are nearly identical in this regard
There will be some sanding of the edges as the epoxy has a lip where it touched the sides of the dam before it finished flowing. I have a small area where I did not get all of the bubbles so there will be a small amount of cleanup there; but I do not intend to sand the surface of the epoxy. I have a precision straight edge that I will use to check the flatness after the cure is complete but the going in plan was by using the low viscosity epoxy only minimal sanding would be required... Lets see how that works out ...
Round 2 tonight went much better. I reduced the amount of acetone to 1/30 of the total weight and no leaks. It self leveled pretty well visually.
Now I will have to wait for a few days before the sanding begins.
In the time being I'm working on the first rail mounting. I have 36 M6 holes to drill and tap in my near future.
Andrew
Good to see it is coming along Andrew.
Hey what's that 'buy me a beer' thing in the header of your posts?
I took advantage of a snow day here in Denver. Woke up with about 1 foot on the ground. I spent the majority of the day sanding and checking. I have both rails now ready to drill. I'm withing a couple thousands of where I want to be now.
Soon the messy part will be over. I can finally see the end of the sanding tunnel.
Andrew
I haven't made much progress in a couple weeks.
Customer orders are taking up much of my spare time as well as a couple of other projects.
I am giving a mini presentation on my project and progress at the Denver Maker's Group meeting tonight. Should be fun.
Andrew
That sounds cool. I would like to go to one of those. Where can i get some info?
Denver Makers
Welcome to Club Workshop
They are the second Thursday of the month every month.
Meeting last night went well. I had several other builders asking lots of questions.
Andrew
I'm declaring my beds exceptable and have started mounting the linear bearings.
Last night I roughly aligned the left rail and clamped it. To drill the holes I used a transfer punch, then center drill, and then used my magnetic drill press to drill each hole after removing the rail. I then chamfered the holes and started to hand tap each hole. I made it through 1/2 of the 36 mounting holes with the tap process.
Sorry no pictures as my fancy smart phone is out of service. I have 3 other cameras but don't know what box or location they currently are. Moving sucks!
Andrew
Finished up the tapping on the left rail and have it now temporarily mounted.
Andrew
At what time do they meet on the second Thursday?