Z-axis Plumb

[Simops]

Ok at first I was not going to post this because felt, as this has been thrashed before (yes have read all the posts I could find), that I should be able to sort this out myself, but damn I'm going to ask for your advice anyway!

Its to do with my Z-axis. When I surface my spoiboard (use a 2.5" Amana RC2257) I get a slight ridge along the Y-axis. Pleae note that my Y axis is factory default X-axis (see pic attached). Brady says that if you can hook your nail it means the spindle is not square. I have measured my nail hook at 5 thou.

If I do as Brady says in one of his posts and use a square against the Spindle I find that this is not accurate for me as my Spindle does not have parallel sides, that is, placed against the left side (which is the side I used to initially square the spindle) shows dead square but then if I use the square on the rght side it is not. It should be the same if the Spindle has straight parallel sides, see pics bellow.

Ok so I decided to chuck in a 1/2" rod (that is a perfect straight rod) into the collet. And place a square up to that. It shows square all round. But then this may not be accurate enough reference as only over a small distance. So I can't rely on the use of a square to 'square' the spindle it seems so will use the surfacing as the guide. No ridges = perfect square.

Indications of having ridges along my Y axis says that I have to adjust the Spindle by unscrewing the 6 bolts holding the Spindle carriage and turn it right as I look at it to square it up. But of course there is no further adjustment available. Before I go to doing something radical as suggested by Gary to make the holes larger or Daniel's Tramel adjustment device....is 5 thou acceptable or am I being to pendantic by trying to get it less than 5 thou??

Thanks

Mike

[bleeth]

Hey Mike:

Bending a piece of rod to use it as a trammel chucked into your spindle is pretty much the best way to check accuracy of z alignment. Personally, if I was getting a ridge that I could catch my fingernail on I would be adjusting too.

[bob_reda]

It could also mean one of your squares are out. My guess would be the larger one, which is alot more common then one may think.

Bob

[damesqua]

Michael,
I'm new to forum, so I learning and may ask basic questions. But, did you level the table surface before checking for square?

[cowboy1296]

This really may not be addressing your problem. But when i had ridges in the past i found out that my rollers were out of alighment. Every time the edge of the table hit a high roller it would cause the table to rise creating the ridge. The rollers are adjustable and really a simple fix. Still working on my second cup so hopefully this made sense.

[Brady Watson]

Mike,
You want to first make sure that your spindle mounting plate is parallel to the extruded body of the spindle. If you measure from the body to the mounting plate, towards the top of the plate using the 'tail' of your digital calipers, and then towards the bottom of the plate to the spindle extrusion, that will tell you how it is running. Be sure the 'heel' of the caliper is square against the body of the spindle when you take your measurement. If you are within .003" of each other, then leave it alone.

If there is any gross deviation, you can adjust it by loosening the plate from the spindle, and carefully assembling it back together again (plate to spindle) while checking for parallel (use only one side of spindle/plate) as you tighten it down. Unfortunately that means pulling the spindle off...but it isn't too bad if you remove the stop bolt at the top of the Z gear rack. Then press all the way down and stick a strip of wood etc between the pinion & rack to hold into place while you pull the spindle off.

Then, when you remount the spindle to the 2x3 Z extrusion, drive the bolts in until they are just barely loose. Then get your (known good!) square and align your spindle to the table. This should get you really close to perfectly perpendicular. Surface the table and see how it looks. If you are still getting lines, 'read them' and adjust as necessary. When you've got it tip top, you shouldn't have to mess with it unless you abuse the tool enough to knock it out.

-B

[curtiss]

Michael,
I'm new to forum, so I learning and may ask basic questions. But, did you level the table surface before checking for square?

Your first table leveling effort is bound to have some ridges of some kind.

After your first leveling, you can lay a flat piece of something on the ridges, and then check the router for plumb with a stiff piece of wire taped to a 1/4" bit.

The tip of the wire should be the same distance above the table in all rotated directions.

[Simops]

Hey guys thanks for the advice......

To answer some of the queries ......yes I checked my squares and they are exact. I have a master engineers square that I know is 100% square and reference my other squares from it. I f I have a square that is not square I bin it! Yes the rollers are checked aligned.....I did this a few months ago when I put a new base on. Yes the table was re-surfaced before taking measurements and after any adjustment (although I have no more adjustment available).

The nuisance factor is the spindle body is not square so cannot reference from it.

One thing is clear from your answers is that the 5 thou ridges are not acceptable. I guess I was in denial because I set up my other machines to 3 thou or less so the CNC should be no different.....just looking at an excuse to get out of doing extra set-up work by hoping someone would say 5 thou is OK:rolleyes:

Brady I'm going to follow what you said.....but I need to re-read it a few times to get my head around the process....

Cheers

[Brady Watson]

.005" out depends on how far away from the spindle nose you are measuring! ;) Shorter bits with show less deviation than longer bits. My advice would be to get a 5" piece of 1/2" or 13mm drill rod (whatever your largest collet will accommodate), chuck it up tight and use that as your 'square reference'.

It is strange that your spindle body would be square on one side, but not on the other. Is it possible that your square was touching the cooling fan housing? That typically sticks out over one of the sides.

Don't drive yourself nuts with this. Get it close, and you'll be just fine on most jobs. You can be out several thousanths before you'll see any ill effects in wood. Only when you start doing large pockets (with large dia tools) will you see any deviation. It is also possible in denser materials like hard plastic & aluminum, but these materials can fool you into thinking you are out of whack if you encounter any kind of cutter deflection, so keep that in mind.

-B

[kubotaman]

An easy way to get the spindle dead on is with a Wixey Gauge. I put a .5 straight bit, as long as possible, into the chuck. I then clean the table off of sawdust and debris. Zero the gauge on the table then put it on the straight bit by way of the magnatized base. I have the bolts slightly loose from the backing plate allowing me to slightly move the spindle to get it to zero. When I have it correct, I then turn the spindle 90 degrees and take another reading. I have even used thin paper as a shim. This way it is quick and believe me is dead on if done correctly. It also allows you to run the spindle anywhere on the table and see if the rails are running correctly. When I surface my table it has absolutely no riges what so ever!!! Hope this helps you! :D

[Simops]

Brady....wilco Roger. BTW if you look at my last pic on my initial post here I did in fact chuck in a 1/2" rod and placed a square to that.....that showed square but I still got the ridges. I think I will lay a 1" board across the table along 'my' X (which is the Y for most botters) and cut a series of squares out. Put my square to the sides and if square all round....leave it at that. If not I'll take off the spindle, re-seat it square to its backer and re-mount and adjust as you suggested. As you said if it is not causing issue than don't fret over it but its just that I like the idea of being as close as possible because once done I don't have to worry about it again:)

Daryl...I do have a Wixey digital angle gauge (I gather that is what you are referring to). I'll try it out as well to see what it gives me.

Thanks guys....

[Simops]

Thought I'd give an update on plumbing the z -axis on my Buddy 48 standard. ...especially for those new to the Shopbot like me (I think you stay 'new' to CNC for many years):) I was finding that I would get ridges after surfacing that would hook your nails as you run it along the X- axis (Y-axis for you guys as I swaped them around for my setup). In the Y-axis (your x-axis) it was ridge less and smooth. See first post beginning of this thread.

So that meant that the spindle was not vertically plumbed to the deck parallel to your Y-axis gantry. The ridges indicated that the spindle had to tilt further to the right but I had already gone as far as the bolt holes would allow!

So yesterday had time to do some maintenance. I removed the deck so that I could get the spindle low enough to gain access to the top 2 bolts ( there are 6 holding the spindle). You have to remove the rack stop bolt first to allow the spindle to move down low enough. I then removed the spindle and had to then enlarge the 6 bolt holes to allow more movement for adjustment. Seems that they should have picked this up in the factory but obviously they do not fine tune it before shipping out. Also took this time to do a re-grease and oil the felt.

Now replaced the spindle, tightened only the top 2 bolts (because you won't get access to them again) and replaced the deck. I then used my 'Align-it Dial Indicator' (see pic below) to act as a trammel.

The nuisance factor was having to remove the dial indicator every time an adjustment had to be done because you have to lower the spindle almost to the deck to gain access to the 4 bolts ( forget the top two). There is a Forum member who has made an attachment so that the spindle can be easily loosened, adjusted and the tightened from the front....excellent...Shopbot should have done this.

Anyhow after a bit of to and froing I got it within 3 thou. Could have gone better but was getting tired of the tedious process. I then surfaced the deck by .05" and this time no ridges to hook your nail. Great....now to replace with new spoilboard and re-surface. The resurface went well, again no ridges. Not perfect mind you but how pedantic can you get....! I was happy that at least I'm not getting nail hooking ridges!:) Using the dial indicator I get, over 48", a max of 5 thou difference. Should I try to reduce that....maybe? But then I would need to get a better way to adjust the spindle like what the other forum member did. It should stay right for a while now but I don't think it would take much to knock it out slightly with use over time.


Cheers

[Brady Watson]

Sometimes the spindle plate is not 100% parallel to the spindle body, so keep that in mind. I've unbolted, mic'd and carefully retightened a number of them over the years to get spindles dead on.

You can get to the top 2 bolts if you remove the top stop from the gear rack (all the way @ the top of the Z rack - 3/16" hex key) and then pull the Z down. Then wedge something soft between the Z and the Z pinion to hold it in place so you can attach the spindle like a gentleman...;)

-B

[Simops]

You can get to the top 2 bolts if you remove the top stop from the gear rack (all the way @ the top of the Z rack - 3/16" hex key) and then pull the Z down.
-B

Yep did that Brady, but you have to remove the deck still to get it low enough.....that is a nuisance and unfortunate.

Cheers

[Ajcoholic]

if you are having a 5 thou high ridge, you are actually cutting a 2.5 thou high ridge which is amplified x2 - correct? Say I use my 1.5" diameter surfacer cutter, and I get 5 thou ridges... the high side is 2.5 up, the low side 2.5 down to give the measured 5 thou (assuming my overlap is zero).

so, over .75" the difference in height is 2.5 thou. Over the whole 48" width of the machine, it would be .16", or 5/32" out. That is less than a degree out of plumb from my calculations.

Now say you are cutting out material from sheet stock - is that going to matter? Probably not.

I had run my spindle hard and stalled out the cutter a number of times experimenting with deep, hard cuts in 8/4 hardwood. I could see my spindle recently cutting a little "out" when surfacing my spoilboard. WHat did I do? Loosen slightly the mounting screws, and tap the spindle with a soft deadblow mallet and re tighten the screws. re test cut. Repeated a few times until the re surfacing left no ridges.

SOmetimes I find trying to measure such things (with a square or pointer, etc) is an expercise in frustration, where as a littlew time spent "trial and error" gets you there fast.

What is important? Not measuring square. WHat is important is no ridges. So adjust in small increments until you get no ridges - then its as good as it will get! :)

[Simops]

Hey AJ that's what I ended up doing........my frustration though was that with the Buddy you can't get to the top bolts of the spindle mounting plate without having to remove the deck so as to lower the spindle down enough......
So to do trial error as you say means that I cannot tighten hard the top bolts because I ain't removing the deck each time I want to make an adjustment (especially 4 x 4 one).
Anyhow did the adjustment tightened the bottom 4 bolts and now no ridges I can hook my nails.
Oh the only other nuisance was that I had to oversize the bolt holes to get enough adjustment.....you think SB would have picked that up in the factory....obviously they don't plumb the Z accurately in the factory.

Hope you are enjoying better weather with Summer coming......it's **** here.....first snow in the mountains already!

[Ajcoholic]

but if you take off the powerstick, and put it back on it doesnt change anything settings wise.. so it is still relatively easy. I put a shop cart in front of my machine to take the weight of the table, when I pull it off but it still is a two person job with my 5' by 6' x 1 1/2" table top.

I found there was just enough slack in the bolts and homes to perfectly plumb my spindle. It is possible that the spindle mouting holes themselves vary by a wee bit, and also the shopbot holes in the plate vary a wee bit and if you are unlucky enough to get two at the either end of the tolerances - you might have to open the holes a bit to plumb it up.

I wont blame shopbot as they dont mount the spindle.

[Simops]

Hey I don't blame Shopbot as the final adjustment for the Z is from the end user. But as a manufacturer they respond to feedback, as I do (manufacturing flight training devices) always looking at improving our products, tweaking things to maintain customer satisfaction and therefore sales.

I feel that the adjustment of the spindle could be made easier without having to remove the deck. You are lucky if you have someone available to help....I don't really and my space is confined so it is a hassle getting the heavy deck off and on when setting up. Thankfully it is not a regular event. Although with basically 4 bolts holding the spindle I think one good knock and it would be out again. I also note from other users that I'm not 'Robinson Crusoe' with the 'running out of adjustment' bolt hole issue.

I grant you that machining wood it may not need as high precision but I machine mostly aluminium parts and so looking at best setup I can get. I'll admit that in hindsight the shopbot was not the best choice for what I'm doing but I wanted the best of both worlds on the cheap so working hard to maintain the highest setup precision I can get.

Cheers