Planer Snipe

[neal560sl]

Forrest,

I did the infeed roll upgrade on my planer as well and it only took me once running a board through without changing depth of cut to realize I couldn't do this anymore. I will say that it definately feeds better than it did with the rubber infeed roll. I too get a fair amount of snipe.

[shopsmithpaul]

A lot of great advice. As a SS instructor years ago I used the planer almost every day. After sharp blades and an occasional tune-up the snipe was barely noticeable. I have used many different planers over the years as an instructor and the SS planer gave the smoothest surface and least amount of snipe. The roller upgrade did help.

I would look for play in the table adjustment mechanism. Also if you are planing wide boards that have a cup in them pressure from both rollers can flatten the cupping. When the board is only engaged by one roller when entering or exiting the planer the board my spring back a little and produce snipe.

Let us know what you find.

[dusty]

Matthias Wandel has an outstanding illustrated explanation of the causes of planer snipe, here: http://woodgears.ca/jointer/planer_snipe.html.

Allowing the end of the workpiece to lift off of the table is only one of the two primary causes of snipe. Like JPG, I avoid this problem by lifting the opposite end of the board very slightly, as it enters and exits the planer (until well balanced on the table).

The other primary cause occurs during the transition from single-roller engagement to two-roller engagement (and vice versa), and has nothing to do with operator technique. The rollers press downward on the table (via the workpiece) with considerable force. When the second roller engages, that force doubles. Because no structure is infinitely stiff, this causes the machine to flex internally, moving the cutterhead slightly farther away from the table, and thus increasing the cutting thickness. Matthias makes a convincing case that this structural flexure is the primary cause of snipe. And not surprisingly, it is a bigger problem on cheaper planers, with lighter frames and fewer jackscrews. (Mathias also has a clever technique for eliminating flexural snipe.)

After tuning up my Pro Planer, I get snipe in the range of 0.002" to 0.005". Pretty good, and indicative of a good rigid frame.

If a Shopsmith planer is generating a lot of snipe, I'd start looking for something wrong with it. I don't see much that could go wrong with the frame itself. But the table jack-screw adjustment could easily be out of whack. The load is supposed to be evenly shared amongst all four screws. But if mis-adjusted, it could be primarily supported by only two screws, cutting the table-system stiffness roughly in half. Worse, it could "tilt" between one or the other of the remaining two screws as the load shifts, causing even larger relative motion.

I think I recall a report of a loose jackscrew on this forum, as well. Anything that compromises the structural rigidity of the machine could cause excessive snipe.

Yes, .002" to .005" of snipe is quite good and except for when doing joinery may be totally adequate. However, .005" may not be acceptable in some applications. I seldom do any work that becomes that critical.

I am curious though about your comment. You say that this is what you have after a tune up of your planer. This seems to imply that left unattended for some period of time, adjustments may need to be tweaked. If this is the case, which adjustments (jackscrews or input/output roller tension) do you believe go out of tolerance and how frequently?

Base on my experience, I expect your replay to be "very infrequently". I bought my ProPlaner in the 1988 or 1989 time frame and I have never adjusted the jackscrews. I have changed roller tension and that turned out to be a mistake. I apparently got carried away and caused more problems than I resolved. Fortunately, I got it all back to normal and I now resist making those adjustments. If I was doing work that needed +-.003" tolerance, it might be different.

PS: Sorry, but this weekend we will be on opposing teams. I normally do not favor the Ducks but this weekend I am a PAC 12 fan. It needs to be shown that the PAC is for real. Beating Ohio would be a good way to do that.

[BuckeyeDennis]

Dusty, I bought my Pro planer used. In the process it was tranported first in the back of the PO's pickup truck, then on its side in the back of my SUV, and then jostled around some more getting into my basement workshop. Even so, it cut pretty well.

When I sharpened the blades, I used Nick's dial-indicator method to set them. While I was set up to indicate, I checked the height of the tie bars above the table, and found some variances between the four different bar ends. So I followed the jack-screw timing process in the manual, and after some futzing about was able to get the tie-bar variances to less than 0.003". I think that is the probably the "secret sauce" -- it means that all the screws are sharing the load equally, with no backlash, and maximizing stiffness.

Unless the planer is moved or otherwise abused, I don't expect to ever need to do that alignment again.

BTW, I've been something of a Duck fan ever since they unexpectedly beat USC back in the Pete Carroll days, shortly after a Buckeye loss to USC. The Oregon coach and the Buckeye coach are good friends. It will be interesting to see if the Ducks are really that good, or if Florida State was that mediocre. On the bright side, if the Ducks do beat the Bucks, it will cause additional embarrassment for the all-too-arrogant SEC!

[dusty]

It could be a good week end no matter who wins the game. I just hope that this is a game worthy of being called "The Championship Game". I hope it is hard fought for 4 complete quarters. If that happens, then we will have had two Championship contenders one of which is "The Champion".

[paulrussell]

Thanks all for the discussion. As to my original post, when I said "help" the board, I meant a slight upward tension on the unsupported end when entering and leaving the planer thus maintaining a slight increase in downward pressure at the end being cut.

I did increase the roller spring pressure to ensure it is as the high end of the 25-30 pound range specified in the manual, and that seems to have helped. Based on the snipe reports of others in this thread, I think I'm now into the average range.

[JPG]

http://www.highlandwoodworking.com/unde ... snipe.aspx

Courtesy Bill from the woodlands!

[fitzhugh]

I recently saw a blog etc. suggesting tacking two scrap pieces to the work piece... Ones that are the same thickness, or just a little more should be fine, but that are a couple inches longer than the work piece. This way they get the snipe instead. Should work in cases where you can't trim off the snipe or reduce it enough to ignore, and when there is room on each side.

Say you are planing a 24" long by 1" thick by 8" wide board... You'd attach (hot melt glue?) a 1" by 1" by 28" piece on each side. Not sure how long the snipe is offhand but the added pieces would be a bit over 2x the length of the snipe.

Haven't tried it but sounds like one that could work where appropriate.

My used planner had awful snipe. I ended up tearing it nearly all apart and found it not too hard, even got it back together! But before that I did greatly reduce e snipe by adjusting the roller pressure via the screw post adjusters on the top (flathead, accessed through holes in top).

The planer manual is good to have. They should have some ready to ship since they had to do a print run to send mine recently.

I managed to plane very curly cherry with almost no flaws after tuning it up, and I had no prior experience, so I'm convinced they are good machines.