Need Help!- Trying to track down where slop is coming from

[basskitcase]

I am almost done with my steel framed router, but i need to figure out why I'm getting some slop.

The build thread with pics is here:

http://www.cnczone.com/forums/showthread.php?t=98950

I have made a few modifications not shown on those pics, including adding steel framing in parallel to the x axis to keep the MDF table from sagging (there is no sag measured with my micrometer now with about 100 lbs downforce). I also added steel tubes to the y axis to stiffen that up as well (i don't think the y is the problem from casual observation)

The problem is that i can take my router, lower it into a workpiece and get as much as .05" of movement in any direction using mabye 5-15 lbs force. Increaseing the force after that point does not result in any appreciable increase in slop.

Any ideas for tracking down what the root cause of this movement is? I have built it from steel because i wanted a sturdy design, and now that i do not have that, i am very disappointed in my creation

[CarveOne]

Originally Posted by basskitcase I am almost done with my steel framed router, but i need to figure out why I'm getting some slop. The build thread with pics is here: http://www.cnczone.com/forums/showthread.php?t=98950 I have made a few modifications not shown on those pics, including adding steel framing in parallel to the x axis to keep the MDF table from sagging (there is no sag measured with my micrometer now with about 100 lbs downforce). I also added steel tubes to the y axis to stiffen that up as well (i don't think the y is the problem from casual observation) The problem is that i can take my router, lower it into a workpiece and get as much as .05" of movement in any direction using mabye 5-15 lbs force. Increaseing the force after that point does not result in any appreciable increase in slop. Any ideas for tracking down what the root cause of this movement is? I have built it from steel because i wanted a sturdy design, and now that i do not have that, i am very disappointed in my creation

I'm working on issues just like that on my second build right now. It isn't easy, but it has to be done for nearly every build. Most of it will be free-play in the carriage to rail contact points if you are using skate bearings or V-rollers. Some parts will be more flexy than you first expected and will need replacing with something stiffer or stiffening by adding more parts to it.

Once the mechanical stuff is stiff enough then the fun begins with the computer and electronics doing weird stuff to your cuts.

CarveOne

[Phife]

Unsupported Y rails with open linear bearings would be my first guess.

Its hard to see but I dont see any supports for your Y Rods, and it looks like you are using open bearings, there will be alot of play there,

Also the wood/bearing sleeve probably has play too..


Grab your router and wiggle it around looking carefully at all the bearings for play/movement.

[basskitcase]

Originally Posted by Phife Unsupported Y rails with open linear bearings would be my first guess. Its hard to see but I dont see any supports for your Y Rods, and it looks like you are using open bearings, there will be alot of play there, Also the wood/bearing sleeve probably has play too.. Grab your router and wiggle it around looking carefully at all the bearings for play/movement.

The Y rails have since been supported with steel tubing and the wooden bearing sleeve has been replaced with a welded steel tube sleeve (this is shown on the later pictures in the build log, but the y supports aren't)

Those were my first guesses too, so i implemented those changes prior to the start of this thread, but i don't notice a significant difference (these would probably show more deformation at higher stress loads than what i have now, but they don't seem to be the culprit behind the wiggling with low stress loads)

What is puzzling is that its got about the same amount of slop in both the x and y directions.

My initial thought was i was getting up and down play in my x bearings, but i mic'ed those today, and i was only getting about 0.005" of play applying a pretty good amout of force.

I think once i get my z axis back on (took it off to paint it) i will try applying forces at the axis' themselves, instead of at the router, so that i can try to narrow down where it is coming from. If i only push on x and i get 0.05" of play, i will know its all in the x. If i push on x and get 0.01" of play, i will know Y and z are the culprit, etc.

[stef_d]

I cant see the pictures from your build (the office firewall, or net nanny)
but i am assuming from the replies that you used bearings and rods. i used those on my first build, and tuning them to run free from play was a real headache.
waht i can only suggest is that you check that all the "wheels" on your carriages are contacting the rod (without any additional pressure), all the way down the table.
in some parts of my setup, i had only 3 out of 4 wheels contacting, in some others, there was 4. this was due to flex in the rods, and not 100% perfect alignement off all the components.
ball bearings and rods are a pain to setup properly.

[basskitcase]

Originally Posted by stef_d I cant see the pictures from your build (the office firewall, or net nanny) but i am assuming from the replies that you used bearings and rods. i used those on my first build, and tuning them to run free from play was a real headache. waht i can only suggest is that you check that all the "wheels" on your carriages are contacting the rod (without any additional pressure), all the way down the table. in some parts of my setup, i had only 3 out of 4 wheels contacting, in some others, there was 4. this was due to flex in the rods, and not 100% perfect alignement off all the components. ball bearings and rods are a pain to setup properly.

Its shaft with open linear bearings. I did do some shimming to my x yesterday, which helped it roll smoother, but i guess i won't know for sure if it helped slop til i get the z axis put back on.