Surface grinder gibs

[Michael Gilligan]

On Michael Gilligan Said:
Vincent motorcycles [and others, I presume] used wires inside drilled oil-passages, as a very effective way of tweaking the cross-sectional area and thus the flow.
Is there a possibility that these wires serve a similar purpose ?
MichaelG.
<strong style=”background-color: #ffffff; font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 14px;”>Edit: __ even managed to find an illustration after all these years !

I wonder if it’s an age thing, I keep finding things in a safe place, and losing them again. 🙂

I’m sure missing images have already been reported by mod(s).
edit; where on earth did this come from, it wasn’t there before I submitted the post?
<strong style=”background-color: #ffffff; font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 14px;”>

Bill

[Michael GilliganParticipant @michaelgilligan61133]

Can someone please give me a shout when this forum starts working predictably ?

MichaelG.

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[Michael GilliganParticipant @michaelgilligan61133]

For info. … The missing Vincent illustration can be found on this page:

https://www.vincentownersclub.co.uk/threads/metering-wires.7342/

MichaelG.

[Steve355Participant @steve355]

On Howard’s point, yes the measuring setup could probably be better, but I think before I try to measure that more accurately I’ve found a bigger problem.

There has been a “chatter” artifact on the grinding I’ve done for a while, which I was hoping would be sorted out once I made progress with the gibs. I was pretty sure it was related to the crank on the table – the chatter was the same size as the teeth on the rack.

But I did a test grind this morning and found a sudden 7 thou jump at a particular point across 6 inches, this was confirmed by a DTI.

what seems to be happening is that the rack is chafing on the saddle. I think I’m not the first person to refurb this grinder, and across time the clearance between the rack and the saddle has effectively reduced.

There is a “shim” under the rack which is now too thick. I need to reduce it (ideally with a surface grinder!). Probably the best thing is to make a new shim from ground flat stock, that is thinner.

But how would I measure the clearance? And what, ideally, should the clearance be, for maximum engagement, minimum backlash, but not interfering with the table and causing chatter?

Hopefully the pics explain ….. the chafing is occurring where the red circle is (at least) confirmed with a feeler gauge.

 

[peak4Participant @peak4]

To give some estimate, I presume the ends of the table were largely unworn and thus provide an initial reference; cumulatively, between the table and saddle, how much did you scrape off?
Try making up just a few short shims that much thinner than the existing one and have a quick play.
You can adjust the shims a bit at a time with green cigarette papers, as they are close to a thou.

Bill

[Pete RimmerParticipant @peterimmer30576]

My rack has slots cut across it between each of the holding bolts to allow for shim adjustment under each bolt, but it doesn’t have that shim.

[Steve355Participant @steve355]

I can’t remember how much I scraped off, it was a while ago, probably a couple of days work with a hand scraper, so not much. The oil grooves on the saddle have virtually disappeared in places which is what makes me think that at some point, in the distant past, the machine was significantly milled/reground. It wasn’t scraped.

I think I might have a go at putting a few washers in in place of the shim to see how it behaves. It might give me some idea as to how thick the shim now needs to be.

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