Spring Line

Re: Spring Line

MikeW

>Interesting question, Stephen.

I've always eyeballed the line and maintained that angle to the best of my abilities through a run of molding. May not match the next run...but it does for the one run.

I kinda like the idea of reflection. I fear in use it would be cumbersome.

Take care, Mike

Eyeball

David Miller from Iowa

>is how grandad did it. Just to get started. The last few strokes he did just by looking at the molding itself to get the look he was after. Can't say I can do it as well.

David

Re: Spring Line

Bob Hackett

>I use it as a reference point to adjust the plane to the work while starting and finishing.

Once I get the feel for how the plane is held I go for it and then check near the end to readjust if need be.

MB

Re: Spring Line

Dean J in MN

>I eyeball it the best I can.

Like others, once the molding is started I don't check as often and let the profile and muscle memory guide the plane.

-Dean

May sound dumb, but

Stuart Hough

>What are spring lines?

Re: May sound dumb, but

Dan Donaldson

>A line on the end of the plane that helps to align it properly for the cut. See the picture.

Re: May sound dumb, but

MikeW

>Hi Stuart--not dumb at all!

The picture below has one of the spring lines barely visable--but hey, the plane is from the mid 1700s!

But you can see the effect of the spring lines. That is, they indicate the angle a molding plane is held in order to produce the intended molding. On this example (the only one I have a picture of--sorry) the line meant to show vertical is barely able to be seen near the bottom "quirk" (in this case the bottom edge of the produced molding).

The other crosses it to show the horizontal. So they form a right angle where they would cross.

In the picture, the weight of the plane and the lower edge cant the plane back more upright than it would be in use. but it was sorta hard to balance the plane and produce the picture when I snapped it.

Take care, Mike

Glad you asked,

Dominic Greco in Richboro PA

>cause' I sure didn't know what a "Spring line" was! :>) But thanks to Dan and Mike I now do!

Dominic

Why?

Ryan Stagg - Cincinnati

>What is the advantage of the sprung ovolo over the unsprung? The stability of cut as you work? -- Pushing into the wood rather than tending to shear off as the profile is established?

Re: Why?

Dean J in MN

>Somewhere there is a good write-up on sprung planes -- Mike, did you cover that in your H&R write up? I know Don could write a book on it.

The spring is there to effect cutting geometry, it minimizes the amount of the profile which, without the spring, would be scraped rather than cut.

-Dean

Re: Why?

MikeW

>Hey Dean--it's in there. If and when I ever get time to get back to it.

But you got it. Depending on the molding shape, there is the scraping tendency. Also, some profiles wouldn't be possible without spring and or the profile would simply take up a lot of realestate in wood. (But that is in spite of the fact an unsprung plane is not as wide.)

Too, the idea--please correct me Larry!--that the spring allows the median baseline to be perpendicular to the sides. Perhaps that is an affect rather than an absolute design criteria.

Too, the iron is easier to both grind to profile and sharpening maintanance. This I think is the biggest issue.

Take care, Mike

back to the grind...ha ha

Steve : I Googled it and got nuth'n. Glad YOU aske

s.mackay@worldnet.att.net

>

Link to article on sprung planes *LINK*

Wendell @ Murphy, TX

>Here's a link to the article that contains the picture Dan included in his post. It cover some of the reasons why molding planes are sprung.

Wendell


Spring Marked Planes

A few photos

Larry Williams

>Most importantly, springing a plane improves the cutting geometry. A sprung plane usually avoids those long scraping cuts. As mentioned earlier, it makes the iron easier to maintain and helps keep a tighter mouth on the plane.

Here are a few photos of a sprung plane and a non sprung plane that illustrate what is going on. The plane without spring is a Casey & Co from about 1857 and the sprung plane is an early 1700's plane by Robert Wooding. Both planes cut almost the same profile.

From the toe, you can see how springing affects the profile on the sole:

In the next photo you can see what happens to the profile of the iron. Keep in mind that the closer to parallel with the sides of the iron part of the profile gets, the more difficult the cutting geometry becomes.

The third photo shows how the mouth opening is affected when the iron is installed.

In answer to Stephen's original question, I prefer to line up the plumb spring line with the edge of the stock being planed. Comparing the two lines gives basically the same results as using a line's reflection in a saw blade.

Usually a sprung profile is at about 30� and not necessarily at right angles to the sides of the plane.

One thing I like about the comparison between these two planes is that it's a great example of how much better the early planes were than their later counterparts. It is, however, unusual that an ogee like that in the Casey & Co plane wasn't sprung even in the 19th Century.