Gallery, Projects and General > The Design Shop
Stepperhead 2
vtsteam:
Thanks Jackary for explaining! :beer:
re. "I do not think the grooves would be any more difficult to manufacture than a dovetail groove. The grooves have to be parallel, but to my mind there are no stringent machining requirements."
I guess you could say that for all lathe bearing surfaces of any sort. Or to put it another way, the precision of the lathe depends on the precision of the bearing surfaces, and stringency of machining (or scraping into bearing) is the measure of quality.
It isn't in the machining or scraping per se I was asking about, rather the means of checking it. Conventionally a straight edge is used on straight profiled lathe sections, but with a curved profile, do you anticipate using a curved profiled straightedge? And when these surfaces wear, as they do in all lathes, and unevenly, as they do generally towards the headstock end, how will this be corrected, even with a profiled straightedge to test, and what kind or shape of scraper?
I remember Mr. Urwick invented the triangular gib for a vertical sliding head on a round column, and your lathes have a clear relationship to his. He patented the triangular gib, but unfortunately it was never widely adopted. Round column Asian milling machines like the one I own would have been a logical beneficiary, but his ideas are largely unused. I hope you have better luck, and besides the desire to do something different, I also admire the beauty of your machines.
jackary:
Hi WeldingRod,
You are correct I did show my topslide with an oval gib but I think I avoided any detail description then. I have been musing over the idea since then and finally decided that it was worth patenting so the application has not yet been published. I think it will be some time before this happens it seems a long winded process. As to whether it is all worth while who knows. One thing for sure is as soon as you show something different the naysayers etc emerge. I will let you all know once it is published.
Screenshot shows a Lever Locking Topslide with an oval gib, lever below feed dial can be lifted to lock the slideways.
Alan
jackary:
Hi vtsteam,
Thank you for your kind comments. As to checking a worn or inaccurate groove I think the procedure could be carried out using a close fitting circular rod and a dial guage referenced to the inner sliding surface of the bed. in a similar way to checking a dovetail groove. The gib can incorporate a degree of flexibility to compensate the slight deviances from a prefect surface.
Screenshot shows the vertical column using an oval gib to lock and locate the column(Lathe bed and headstock block not shown)
Alan
vtsteam:
Thanks Alan for the explanation of how the groove might be measured for truth. :beer:
I also believe that there's a difference between nay-saying and the honest curiosity aroused when something new is presented, and I hope that positive questions presented with respect can even be seen to be of value sometimes. In the former a person wants to challenge or belittle, and in the latter a person just wants to understand. No drawing can explain fully what a person envisions, nor can any inventor fully imagine all possible situations or issues, and questions help fill that gap for both.
I was once called in to a job interview as a technical writer. It turned out at the interview that the job was really for patent writing. Though I needed the job, I declined it as not qualified. I was hired anyway by the CEO as a project engineer, so, apparently, honesty wasn't a detriment to employment. But I did do a fair amount of research into patent writing requirements after, mainly for personal reasons. I was eventually discouraged from patenting as not worth the effort for an individual by Don Lancaster's internet postings on the subject. I now think there are better ways to profit from ideas. I don't know if you've looked at Mr. Lancaster's site already, but I think it's good to get that perspective on what's involved with not only obtaining one, but also profiting from it, and defending it.
Anyway, off that subject, I'm going to admit I'm still a little confused about the gibs and their groove's precision in relation to the round column. So I hope I'm not becoming too tedious. I think I understand that by canting the gib in its groove, it's a means of getting a good fit tangential to a round column. If tangential play is taken up by canting the gib, does its wear surface become only the corners of the gib in direct contact with the groove?
I realize the cant angle would be small, if fit was good. But would this nevertheless accelerate wear on the gib, when compared to a conventional flat gib (or in the case of a round column ways, a Urwick flat triangular gib) with full contact area?
Or am I totally missing the mark -- the gib isn't canted to take up play?
jackary:
Hi vtsteam
This was my explanation and there is no play when the column is locked.
The vertical column grooves would form a full circle when aligned but are purposely mis-aligned to form an offset aperture by the oversize first gib. A secondary gib is added below the first upper gib which can be rotated to urge the offset grooves into alignment, therefore locking the column in its slideway. The gib can have a simple oval profile or be more profiled to match the groove surfaces giving closely matching contact surfaces.
Alan
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