Thread: HM46 Z axis Gib screw issue

The head of the screw is meant to push on the gib, not go behind it.
You need to work out which end of the gib is the thin end, then unscrew the screw on that end and then do up the screw at the thick end.
The two screw just hold the gib between them.

Stuart

That makes a lot of sense Stuart (thanks). I had no idea there was another screw. In my mind I pictured it as being tapered and about half the length if the dovetail wedged in there..

I was going to comment earlier but Stuart covered it all.

While your in there support the head on some blocks of wood on the table and take the gib completely out to give it and the dovetail on either side a clean. A bit of kero in a spray bottle of WD 40 to flush out the crap left in there, and then re oil the lot and adjust it up.
Taking it apart will also give you a better idea how it works and what it looks like. Some times there can be a burr on the gib or screw, so file them off if you see them.

Dave

Originally Posted by Dave J

I was going to comment earlier but Stuart covered it all.

While your in there support the head on some blocks of wood on the table and take the gib completely out to give it and the dovetail on either side a clean. A bit of kero in a spray bottle of WD 40 to flush out the crap left in there, and then re oil the lot and adjust it up.
Taking it apart will also give you a better idea how it works and what it looks like. Some times there can be a burr on the gib or screw, so file them off if you see them.

Dave

Thanks for the tips Dave. I will pull it apart and give it a good clean. I am a bit disappointed with the whole head setup on these machines. If I gently pull down on the head I can read a good 0.07mm of slop. I guess that is what one gets when the head is only held on with 3 bolts. I am now having dreams of a BM-30A! Unfortunately I need a garage extension to cater for it..

All you can do is work with what you have. The HM50-52 mills only have 3 bolts as well, one either side and one underneath what where they thinking when they designed it as the one underneath does nothing for holding up the head, LOL

If you go right through it and fix a little of each connection point you will get a lot of it out. The trouble is that these mills and a lot of others are assembled in a dirty factory in China with no care given to cleanliness. Go right through it and clean it all out and there will be a difference.

We would all like a larger mill, but like you said we need to fit it, move it, and then pay for it. The 30 is only the base real knee mill, so where do you stop, LOL
If they took more time in the fitments of these machines would be much better.

Dave

Hi there,

Due to the weight of the head, it can be difficult to get a "feel" of the tightness of the gibb strip and how the fit is. I would organise an engine crane or other lifting device and completely remove the head, leaving only the Z dovetail mating part. Any adjustments you make will be aesy to gauge and feel. Actually, if you remove the bolt that holds the Z leadscrew nut, then you have the freedom to slide the assembly up and down the Z axis which gives a better appreciation for fit and adjustment.

Cheers,

Simon