R. O. T. or ball park setting for .....
 

Reference 15 Clones:

Is there a rule of thumb, or a ball park setting for the distance the needle bar rises after BDC, when the hook point is centered behind the needle?

And is there a rule of thumb, or a ball park setting for the needle depth at BDC?

I've got several clones, over a half dozen, and they are not the same. Some work good and some are cranky, but no two are exactly the same.

Some have timing marks and some don't. But even with those that have timing marks, when the timing marks are lined up the needle points are not in the same place relative to the hook point.

Joe

In all the machines I've timed, the manuals or guides say that the needle hole should be 1/16" below the hook point. Just checked the 15-91 adjuster's manual (p.25) and it says the same thing, so I'm pretty sure it's right.

Mike,

1/16", OK, I'll put that in my memory box and check those machines that actually sew properly. From my minds eye they were very close to that.
Then I'll recheck the malcontents and go from there.

Thanks.

Joe

Joe,

For timing the industry standard for needlebar rise from BDC is .093mm. At this point the tip of the hook is just barely behind the needle and usually in the middle of the scarf when set at straight stitch and center needle position.

The hook timing is always set before the needle height. Then it will be easy the gauge the height for the needlebar.

Cathy, are you sure that .093 mm? 93 thousands of a mm??? A mm isn't very big to start with and that .093 would be just a hair over 9 hundredths of a mm.

Could it .093" maybe?

Just checking to be sure

Joe

Oh, and, on the clones I'm working with their hook drive shaft connections are all pinned solid. No way to adjust the hook timing that I know of. Is there a way I'm missing?

Joe

Yup, .093". Brain out to lunch again. Thank you for pointing out my mis-typing.

Cathy

No, you are not missing anything. The machines that are pinned are considered to never go out of time.

Cathy,

I did some measuring of the needle bar BDC to needle alignment on three different machines and got three different measurements. I think the shortest stroke was .059" and the longest was .090" with the middle one at .081". I know the needle bar can be adjusted up or down, but I can't see any way to adjust the stroke of the needle bar.

So what to check next?

Joe

Joe,

The .093" is an industry standard, but it is also sometimes to the factory assembly person a starting point. If the hook is pinned, then the only thing you need to be concerned with is the needlebar height. Put the hook tip behind the needle, then set the height so the tip of the hook is about in the middle of the scarf. On these old straight class 15 machines, Ray White says the timing is not as critical as the zig zag machines. He said that your difference measurements are acceptable. Remember. If it ain't broke (it sews well) don't fix.