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View Full Version : Is it possible that the X axis ways are not accurately ground?



phantomcow2
09-22-2005, 09:05 PM
I have an X1 micro mill, I am very happy with it except for one thing.
That is, about half way throught he X axis travel, when the table is moving toward the left, it becomes slightly more difficult to turn. Then as you keep going it becomes hard enough you need 2 hands to do it comfortably. And when you near the end, its so hard that you need two hands and i am shaking the entire table.
I was told it was the leadscrew binding, i realigned the nut and bearing block. Still nothing.
So i did a little experiment, i removed the leadscrew all together and tried to see if i could just slide the table by hand. Nope, all was smooth until i felt more and more resistance until with all my might i could not push the table any further.
The only thing i can think of is that my table is not ground entirely flat, its at a slight angle. Is there anything i can do about this?
At school they have a surface grinder, i have never used these before and have no idea what they are used for, would that help?

rustyolddo
09-22-2005, 10:07 PM
Oh yeah. It's possible & probable. Problem is you have to figure out where the problem is. Might not be easy to fix with just a surface grinder especially if it's in the dovetail. You can use Dykem to find where the tight spots are and proceed from there.

phantomcow2
09-22-2005, 10:17 PM
what do you mean use dykem to find out where the tight spots are?
Like apply the dykem to the contact areas and see where it scraps it off?
We have a full sized bridgeport mill with dovetail cutters at school, is "refacing" the dovetails a possible solution?
I like that dykem idea, i use that stuff a lot at school but i should pick up a bottle myself.
Thanks for the reply,

mxtras
09-23-2005, 12:00 AM
Prussian blue, not Dykem.

Scott

JFettig
09-23-2005, 12:58 AM
I think all you really have to do is loosen the leadscrew mount, move it around and find a good spot where it moves well, same with the leadnut mount. That is typically the problem when it happens to me.

Jon

Bloy2004
09-23-2005, 05:33 AM
Check the inside "VEE" of the dovetails... I had a similar problem with a mini lathe and found that the point of the outer dovetail was rubbing on the inside of the mating dovetail. I had to groove it out more and also filed off the shart edge of the outer dovetail. Once the surfaces of the dovetails were allowed to mate, the sliding action was smooth from end to end of travel. It took me a while to find that the groove of the inside dovetail was machined without adequate clearance.

phantomcow2
09-23-2005, 06:13 AM
I think all you really have to do is loosen the leadscrew mount, move it around and find a good spot where it moves well, same with the leadnut mount. That is typically the problem when it happens to me.

Jon
I thought it was, and i have done that many times. But the fact that i encountered the same problem WITHOUT the leadscrew all together, leads me to believe otherwise.

phantomcow2
09-23-2005, 06:15 AM
Check the inside "VEE" of the dovetails... I had a similar problem with a mini lathe and found that the point of the outer dovetail was rubbing on the inside of the mating dovetail. I had to groove it out more and also filed off the shart edge of the outer dovetail. Once the surfaces of the dovetails were allowed to mate, the sliding action was smooth from end to end of travel. It took me a while to find that the groove of the inside dovetail was machined without adequate clearance.
I think i get it, so at the factory the dovetail cutters did not move in deep enough for part of the travel, causing the binding. Or perhaps the table was not square with the cutter, this seems likely because the gibs are extremely tight near the end of the travel. But slightly loose toward the start

pacosoide
09-23-2005, 08:06 PM
I agree with the previous observation. I would loosen the gibs and see if you still have the same problem. Most of the time is the gibs too tight on one side.
Jose.

phantomcow2
09-23-2005, 08:21 PM
I agree with the previous observation. I would loosen the gibs and see if you still have the same problem. Most of the time is the gibs too tight on one side.
Jose.
If i loosen the gibs, it works alright. BUt here is what leads to suspect an innacuracy
On the part where it starts to be harder to turn (about half way through its travel), the gibs tighten up, then if i keep it going to the max where its the hardest to turn, adjust the gibs like i normally would, there is play when it comes to the other end of the travel. Clearly an angle exists which should not
I sanded down what i could, but i want to see if I can use hte surface grinder and dovetail cutter at school.
I really dont want to buy another table because in November the long table for the micro comes out and i will just buy that.

phantomcow2
09-23-2005, 08:24 PM
ANd assuming the dovetails and all are not accurately ground, and i cant do it at school for liability ot whatever, what would I be looking at for having a machine shop do this?
I can get a dovetail cutter no problem, its another mill i have a problem with. A friend of mine is deciding on which mill to buy, maybe i can hurry him up and use that :)

motomitch1
09-23-2005, 09:30 PM
Sounds like your dovetails are not parallel.If You can get two .375 dia. dowel pins and set them down inside the dovetails you can mic over them.Do that on both ends and the middle.you can see how bad it is.

phantomcow2
09-23-2005, 10:06 PM
Sounds like your dovetails are not parallel.If You can get two .375 dia. dowel pins and set them down inside the dovetails you can mic over them.Do that on both ends and the middle.you can see how bad it is.
Dovetails not parallel, that seems to be correct.
I never thought of that dowel pin idea, thanks. When you say you can mic over them, do you mean check measurements with a micrometer? My neighbor is a retired machinist, he can probably help me here.
Can non parallel dovetails be solved? Or am i better off bitting the bullet and getting another table

itsme
09-24-2005, 03:17 AM
Hi,

Before you go and get another table or modify your current table, why don't you speak to someone where you bought the machine. Surely if you can prove to them (the difficult part) that the dovetails aren't parallel, they should do something about it, since that would have to be classed as a defect. I'm guessing the machine is still quite new.

Regards
Warren

Torsten
09-24-2005, 04:15 AM
Difficult to say what is going on here.
If this is a older Machine it is very common to wear more in the center Area of travel because this is the part used most frequently.
If the Machine is of newer age then yes there are some lemons out there that are on the maximum of the manufacturing variations or tolerances.
Buying a new Table may not solve the problem if the cause is in the saddle.
Some times this is caused by a loose tapered gib that has to much slop back and forth
turning in one direction will slide the gib back allowing more clearance while the other
direction will slide the gib in and reducing clearance of travel.
If the problem still persists I would use the prussian blue and see where the tight spots are then scrape them with a scraper untill a even wearpattern is obtained.
Good Luck

phantomcow2
09-24-2005, 06:42 AM
I actually bought the machine off ebay, the previous owner said he hardly ever used it. I believed him when i still found red packing grease on some parts of it.
The saddle is 4 days old, i doubt thats an issue. Thanks for replies

trubleshtr
09-24-2005, 05:39 PM
Do you have a way to set up a dial indicator and run it on the dovetails in question?
maybe the saddle is not only parallel to the ways but out of square side to side?
stick the indicator in the spindle and run the x,y,axis around and see what you get?
just a thought
good luck.

phantomcow2
09-24-2005, 05:51 PM
Well the thing is that the saddle is brand new, and it did htis with the old one too.
I am going to test the depth of the dovetails on both ends to see what I get. Same with the saddle

ViperTX
09-24-2005, 11:18 PM
So, check that the dovetails are parallel to each other and use a straight edge to check that each dovetail is straight.

phantomcow2
09-25-2005, 08:29 AM
I checked everything with my calipers, the saddle is right on. I put permanent marker all over the contact areas (could have used dykem or something of the like but its all at school). And i could see where it was scraped off, I measured the dovetails on the table itself...loe and behold I have a problem.
Thanks all for your advice

anoel
09-25-2005, 11:25 AM
Do you have a local Harbor Freight store? If so call them and see if they would let you exchange it (the whole machine, they don't do parts at the local stores). Or you can hold out and and order one of the new kick ass extended X axis kits from LMS when they arrive in a month or two. (I'd sell you my standard table very cheap after I convert mine. But again that'll be Christmas time.)

phantomcow2
09-25-2005, 12:01 PM
I envy all of you who have HF stores nearby...
THe nearest one from where I am is Albany NY, probably 300 miles away.
I was not planning on buying another table because I too am waiting until November for that X axis extend kit. I am setup to be notified when its in stock, it would be great to order frm Arc euro trade but shipping from the UK is over 90 dollars :(.
Its just not worth spending 50 on a table i will use for 2 months then ditch for a bigger and consequently better table

chas
10-26-2005, 01:10 AM
<Or you can hold out and and order one of the new kick ass extended X axis kits from LMS>
Who is LMS?
Is this for the round column mill?
Thanks

phantomcow2
10-26-2005, 06:25 AM
LMS is little machine shop, the coolest place on earth :cool:
They import replacement parts and all sorts of things for Sieg machines. And the micro mill is square column. Its Harbor Freight #47158

chas
10-26-2005, 09:25 PM
Is the square column micro mill smaller than the round column -
Harbor Freight #33686.

phantomcow2
10-26-2005, 09:28 PM
Is the square column micro mill smaller than the round column -
Harbor Freight #33686.
Oh yes, much smaller. THe micro mill is, well, not micro but not big either. Its about 100 pounds. Its Harbor Freight 47158. But with the Y and X axis upgrades its got a decent amount of travel, about 13.5" in the X and roughly 5.5-6" in the Y.
For what it is, thats pretty damn good. Its a brute for its size, i can take deep cuts in aluminum with minimal problems.

chas
10-26-2005, 09:41 PM
Wow, I guess that I will have no problem milling aluminum with
mine.
So I guess that your using steppers as aposed to servo's?
Did you replace leadscrews for ballscrews?

phantomcow2
10-26-2005, 09:53 PM
Aluminum is not a problem. THis is no bridgeport obviously, but its geared low so it handles a 1/2" end mill no sweat. The main limiting factor I have found is chatter, which can be reduced by adding concrete to the column and keeping the gibs snug.
Using steppers, its not worth the money for servos. Not saying that servos are not worth the money, but its not needed for this mill. Who cares about 80IPM rapids when the mill has got somethonmg like 8" for the X anyways.
I kept the stock leadscrews. They are working alright now, give me minimal backlash. When the screws wear out or I get frustrated with them, i might look at ballscrews. Well actually i already looked at ballscrews, but I want to use what i have first. Maybe i will just get new acme screws with a higher lead and anti backlash nuts. I dont want to spend huge sums of cash on this mill, eventually i will sell this and go for something bigger. This was just a learning experience (and that it was)

chas
10-26-2005, 10:29 PM
It sound pretty cool.
I'm just starting with my round column mill.
I'll be using ac servo's with Rutex drives.
This is my 1st mill so I'm not sure what to
expect for milling results, only experience is
with router table cnc's.

phantomcow2
10-27-2005, 06:25 AM
WEll if you have got that round column mill, expect to take a hell of a lot more cut than with the Micro. Most of what i will cut is aluminum and plastics.
You might look into a good book, they tend to be written in the not so reader friendly way. But at school we have one "Machine shop practices", it has everything you need to know with pictures. THers a bunch of books out there to help you get started with milling. The most efficient way to learn though is just power on the mill and produce something, using common sense not to cause harm. And then just look online for how to use various tools which may not be entirely obvious.