Member postings for Hopper

That is horrific. Is that on the sliding surface? If so there must be something horribly horribly wrong to do that to a gib strip. You need to check the cause of that before it does it again to your remachined surface. Did you do the checks with a feeler gauge per the video posted above?

Or was that groove in the gib strip machined in there at the factory for the ends of the gib adjusting screws to locate on, on the non-sliding side of the gib strip?

Supposedly it can blow swarf into the ways etc. I use various small brushes instead and leave the vacuum for final clean up at the end of the day.

I don't know how long they would last for sure. The only way to really tell would be to run them for an hour and inspect carefully. May well be all right for occasional emergency gen set use. But I would not expect them to last too long if not hardened.

I don't have trouble threading silver steel but use good quality dies. I don't know if high tensile bolts would have enough carbon in them to harden like silver steel. I think they are more of an alloy steel than high carbon content, but have never looked it up. I am sure it is out there somewhere.

1/4 UNF tappet adjusters from something else might fit? Lister?

Thanks. Although, I don't recommend his use of channel lock pliers to undo the gib screw locknuts. Poor guy is in America and has not yet heard that you can buy metric spanners for "furn" machinery. But his use of feelers to find where the cross slide is riding is spot on.

I reckon you could file the top off that gib strip if you had to, if you have no milling machine. I notice too that the gib strip doesn't have the drilled divots for the gib screws to engage with. So I guess by nature it will push that gib strip downwards against the base when you tighten them up. Which should work. But is the opposite of the Myford philosophy and GH THomas who took it one step further and added two dowel pins to give absolutely positive gib strip location.

Edited By Hopper on 20/02/2023 10:15:50

If locking the cross slide makes the problem go away, as you have found, then it is hard to think how something like the feed worm wheel running eccentric could be causing it in this particular instance. It would seem the problem is more likely something to do with the cross slide moving cyclically under the load of cutting forces.

Try a few more tests with the cross slide locked and if it confirms that fixes the problem, you should look more closely at the cross slide before ripping into more complicated things. Rule 1 of troubleshooting: Always eliminate the simple stuff first. (Surprisingly often, this will fix it.)

You said you could not get a happy medium on the gib screw adjustment between too loose or too tight. That sounds like something is not right in the dovetails/gibs/ways area. It might pay to check it all carefully for burrs and sharp edges etc and smooth them down with a dead smooth file or a small slip stone.

The other thing to check, which I have found dodgy on some cheaper lathes is the fit of the gib strip. It should have small indents drilled in it for the screw ends to seat in. The ends of the screws should be domed to fit nicely into those indents. And, very importantly, the gib strip should have clearance at the edge so when you tighten those gib screws it is not pushing the gib strip up against the bottom of the dovetail of the half it is supposed to slide against, thus causing binding. And make sure there is no gap between the horizontal flat surface on the carriage and the mating surface on the cross slide.

This video gives a bit of a run through on things to look for on typical Chinese cross slide set up and the pitfalls that can occur. It shows how an incorrectly fitted gib strip can cause the cross slide to ride up on the edge of gib strip instead of on the flat way surface.

Edited By Hopper on 20/02/2023 08:26:53

Or boring it out oversize, pressing in a bushing and reboring the hole concentric with the worm or gear teeth.

They might last an hour or two unhardened or maybe a bit more. But they might mess up the ends of your pushrods and fiinish up costing you more money in the long run too. I would buy the correct parts. They take quite a hammering due to the tappet clearance and there is a reason every manufacturer hardens them..

You should be able to set which browser and search engine you want to be the default in the settings menu somewhere. I always have to google it, something like "how to set default browser/search engine in Windows xx" as I always forget.

Then you have to be careful whenever Windows does a major update because it tries to reset the default browser to Edge. Carefully read the options on the set up menu that pops up after the update and unclick things like "Make Edge/Bing the default browser/seach engine".

But Microsoft seem to have set it up so you can not uninstall Edge from your computer completely. You can not use it by setting another as the default, but Edge is still sitting there in the background.

Edited By Hopper on 19/02/2023 11:34:37

Those gentlemen on the subcontinent are at it again. This popped up while viewing a posted video in another thread so rather than hijack that thread, I think this effort deserves a thread of its own. Not just for the amazing machining and welding skills under very basic conditions, but for the hair-raising WHS aspect of whirling truck crankshaft and human hands and tools interfacing perfectly. Especially the external lapping of the big end journal -- without setting it to rotate concentric first! And all done with a nonchalant durry hanging out the corner of his mouth in the time-honoured manner.

Edited By Hopper on 19/02/2023 08:50:06

Edited By Hopper on 19/02/2023 08:57:39

Backlash in the feed screw and nut alone should not cause that problem. Most lathes, and pretty much all old lathes, have that much backlash or more.

Try setting the gib screws on the cross slide so they are bearing evenly but with a little bit of drag so it stops the cross slide moving quite so freely. While you are at it, do the topslide gib screws and the carriage gib screws as well. Topslide is best locked solid when not in use.

And always be sure when adding some depth of cut, to wind the cross slide inwards only. If you go too far, don't just back off the dial a few graduations, but take it right back out past the backlash and then re-approach the desired depth of cut winding the cross slide inwards.

I get a finish like that on my old Drummond M-type when the adjustable tapered bronze headstock bearing bushes need nipping up a bit. Tightening the bearings fixes it every time. (Not that often but have done it several times over the years.)

On a modern taper roller bearing headstock it should be easy enough to measure with a dial indicator reading directly on the spindle or chuck mounting flange. Clamp a piece of bar say 12" long in the chuck and try yanking it up and down on the far end while reading the dial indicator on the spindle or chuck flange. With taper rollers there should be zero movement. Myfords etc with plain bearings, maybe half a thou or so.

The crystals come flat, with the OD slightly larger than the hole they fit into in the bezel. You then have to press them in using a domed former. The trick is getting the crystal just the right amount oversize and also in most cases the OD needs a chamfer so it grips in the groove in the bezel.

You can use the tailstock of the lathe to press the crystal into the bezel held in the chuck, with suitable domed former held in the tailstock chuck or taper. Watchmakers use a handy dandy little hand press to do the same.

Best source of info and parts I know on this stuff is here at Long Island Indicator Service LINK

Fitting a crystal page is here LINK

Try adjusting the headstock bearings a little tighter.

Ah yes. Tutto bene!

Ah OK that makes more sense.

Can the supplier of the valve give you any info on what clearance to run?

At the price (not the postage!!) and at the news of the stellite pad coming off the end of the stem, even under severe hammering, I would have to wonder about the quality of the valve. Good quality Harley valves run about $50 each and Norton valves can be as much as almost $200 each for the super magic ones. But I suppose you don't get much choice with ancient Guzzi parts. I have seen a few hung up valves on Harleys and Brit bikes but have never seen a pad come off the tip of the stem. But not sure they even have such a thing. I don't suppose you have an alternative supplier ?

Yes surprising your machine shop would make it so tight on such an old machine. If they opened it up to 3 thou after the first seizure it must have been 2 or 2 somehting to start with. Did you find what the original Guzzi clearance specs were?

Edited By Hopper on 18/02/2023 07:30:34

Clearance of .003" on an unlubricated valve stem could quite possibly be too tight, I reckon. My 1977 Harley with cast iron heads has a factory spec of .0035 to .0045" valve stem clearance, new from the factory. Then they allow another 2 thou of wear beyond that before replacement is called for. And that is in a much more modern engine with higher revs, enclosed rocker gear and pressure fed oil to the rocker spindles and arms which then sprays out over the guides and valve stems.

So I reckon you could try something like .005" clearance and see how it goes. Maybe even a thou more. Just make sure they give the valve stem a darn good polish up after it has nipped up so there is no roughness left to start galling again.

I don't know if the chrome is really visible on stainless Harley valve stems, I never really looked at them that hard. What brand of valve did you use? I think most of the high performance aftermarket valves like Manley come with chrome stems if they are stainless. But they are made for high rpm high power use with heavy valve springs etc so your lovely olde-worlde single banger will probably not need it.

It is a common problem with modern machine shops working on true vintage machinery. They think that because they have done work on Honda 4s and Kawa 900s from the 1970s, and maybe a few old Norton Commandos or BSA twins and the like, that they know all about "vintage" bikes. But those old engines from the pre-War era ran everything loose and are a whole different world again. They were still operating very much in the steam age to a certain extent . They did not have the machining or the metallurgy let alone the lubrication, to run modern tight clearances.

Edited By Hopper on 18/02/2023 04:17:31

Edited By Hopper on 18/02/2023 04:29:00

Thanks for reporting back on what that lever is for. Quite intriguing.

And if you do a google search for "Digital outside calipers" you will find this interesting mix of new and old tooling. Internal version is also available. Looks very handy for measuring oddly shaped things. And not very expensive at circa 30 Quid.

I have seen the figure 8 type referred to in an American cylinder head porting book as "indicating calipers" but a google search shows nothing under that except normal digital calipers and the above.

Edited By Hopper on 18/02/2023 03:57:45

Yes, mobius was the first word that came to my mind when I looked at it.

Such double ended calipers are used by cylinder-head modifiers on car and motorbike engines for measuring how much thickness of metal is left between an enlarged port and thin air or the next port etc when grinding out the ports. So might be available from automotive tool suppliers.