Warco GH18 Milling Machine

Hi Guys I am having some very frustrating issues with my mill regarding the fine feed adjustment.

Every time I adjust the depth of cut the quill drops 0.5mm I then have to wind back take up the backlash and then reset the depth again. This problem manifests its self virtually every time I adjust the cut depth and to be honest it is making the mill very inaccurate and difficult to use. Has anybody else experienced this issue and managed to rectify any advice or suggestions are vey welcome.

I try not to use the quill for cutting-depth adjustment - it stays firmly retracted and locked off, if at all possible. But I have ‘knee’ machines, so the table can be shifted. Is the head on your machine not able to provide cutting increments?

I have a WM18, which like the GH18 has no knee.

I move the whole head on the column for large movements and only move the quill over short distances whenever possible. The quill is OK for drilling, but it's best not to extend it far when milling.

I haven't had any trouble with backlash, but I always lock the gibs before cutting. Gib locking is important on Hobby mills because they're relatively lightly built. The head is locked with the two long-handled Bristol Levers top and bottom on the right side of the column, while the quill is locked with the single Bristol Lever on the left side of the head.

Dave

An update on my post from yesterday, out of sheer frustration I decided to drop the quill assembly out of the head and found that there is some slight scoring on the outer sleeve that runs up and down inside the casting of the head.

On further investigation I have found some very slight burring on the inside of the casting where the guide screw enters and also round the area where the rack and pinion is exposed to locate on the quill this would I believe create enough drag to be the cause of my problems.

My plan going forward is to remove said burring and also whilst the head is in bits so to speak, replace all the bearings in the shaft/quill and gearbox. So hopefully future proof my mill.

I have now manufactured a new guide pin as the original one was a bolt turned down so was a very sloppy fit in the keyway, new SKF bearings ordered, hopefully be here for weekend. Then I will rebuild and hopefully all will be good.

How did the modifications go?

How easy is it to drop the quill out - and get it back in again?

I have the GH18 too, and have the same problem. It is getting worse with time.

My solution has been to fit a dro and only ever adjust the height when not over the workpiece.

It is a shame as this does spoil a mill that I am otherwise very happy with.

My RF45 mill (similar mill/drill to the Warco GH18) only has a fine feed on the quill. No knee and the height adjustment on the head is not accurate and only used for the initial set up.

It is fitted with a DRO to monitor depth but the quill can be lowered accurately by a few thou for fine cuts.

My previous mill, a Sieg SX3 also had an accurate fine feed on the quill.

Hi dropping the quill was very simple. I drained the gearbox of oil, lowered the head as far as it would go on to some wood to protect the table undid the spring loaded tensioner on the left hand side this is the fiddliest part of the operation as the spring has a tab with a slot in it that you have to remove from a screw that is in the shaft of the lowering mechanism. 

                 Then undid the four bolts on the block holding the fine feed and main feed. This allows you to slide the quill lowering mechanism out from the head, I then slowly raised the head while supporting the quill, on the left hand side of the head in front of the tensioning spring you will see where the guide pin is screwed into the head you have to remove this to allow the quill to slide out of the head (there are two allen screws in this hole). The whole operation can be completed in under twenty minutes.

         I manufactured a new guide pin, deburred the keyway and also inside the head where the quill slides up and down. Re assembling is just the reverse of the above operation, my mill is now better than it was, not perfect I hasten to add but definitely improved.

         If you watch the youtube channel Machining With Joe he has done a video of the above operation on a Warco mill (not a GH18) but it is an identical setup to ours. Let me know if you have any issues and I will try to assist, although I doubt you will have any as it is a very simple operation.

Edited By John Templeman on 05/02/2022 06:42:26

Thanks john.

I have only just changed the oil so will put up with it for now.

As it did not happen when the mill was new, and has slowly got worse, I was guessing it was muck that had got in there somehow.

Did you manage to identify the cause of the problem?

I think it was a combination of muck, burrs on the guide pin and also on the keyway.

You can check the guide pin by just removing it with the quill in situ as it just unscrews, if it is a bolt turned down like mine was you may find that it improves by replacing it with a properly machined pin.

I think the main issue however is the backlash in the fine feed mechanism which you can mostly fine tune out by adjusting the tension spring and also slackening and repositioning the block on the the right hand side of the head.

I have played with the spring tension before but it did not help.

I can't remember if I have tried adjusting backlash before, but I will try this tomorrow, and make a brass pin too.

Thanks.