View Full Version : Shapers: reflecting on finishes
I have been working on improving the range of finishes and the quality of same that I can produce on my shaper. I came up with a method today that is as old as the hills but is perfectly suited for use on a shaper. I'm sure this isn't anything new but I haven't seen it or read about it.
Example of the finish, only partly done and moving from far to near:
Here is another look. The finish varies because I was testing different variables.
This finish is the result of burnishing rather than cutting. The shaper is a natural for burnishing plane surfaces. The tool is simply rounded and polished to a reflecting finish.
After testing several lubes I found the best is EP Gear lube. I tried wheel bearing grease and ended up ripping a strip across the test piece when it galled. I also found the stroke rate doesn't make much difference but a slow stroke will help to minimize wear on the tool. Pressure is a try it and see effort. I filed a very small break at the ends of the work to make a small ramp for the tool to climb on the work. In this application the tool must be aligned directly below the pivot point of the clapper or it will not bear on the work.
I have found a minor problem that becomes much more obvious with a specular finish. My Whipp shaper is producing clear periodic marks that are directly timed to the gear teeth on the bull gear and pinion meshing. This becomes much easier to see with a specular finish. In this pic the effect can be seen as vertical striations in the finish. It can't be felt or otherwise measured with ordinary equipment but on a specular finish any deviation from purely flat is easy to see.
I can't think of any way to alleviate this. Does anyone have any ideas?
07-07-2007, 06:52 PM
I haven't noticed this with my Ammco - it has a fibre bull gear but is fairly "loose" in fit to the pinion. I keep these gears well greased.
Some options to play with:
1) Try running the belt from the motor to the countershaft fairly loose - this sometimes helps on gearhead lathes. I do this also to lessen the chances of stripping the bull gear when I make a mistake - yes, it has happened - mistakes, that is!!!
2) Check the gibs on the ram - I don't know if your machine has V-ways or square ones. Can you move the ram vertically (dial indicator to vise)?
I am using SAE 20 Way oil. Then again my machine is an order of magnitude smaller than yours.
All the best,
07-07-2007, 06:54 PM
Another thought. Maybe with the burnishing action one has to use a much higher speed.
Your Old Dog
07-07-2007, 07:15 PM
Charge a small piece of 8 oz leather with green chrome bufing polish. Now drag the cutting bit backwards across the leather two or three times with some serious downward pressure. The object is to put a mirror finish on the area just behind the cutting edge without dulling the cutting edge. If you have a piece of 4/0 jewelers paper you can lay it on a surface like masonite and do the same thing with just about the same result.
The finish you see is a result of what is imparted to it by the cutting tool. If it's ratty, you get a ratty finish. If it's well honed and a bright heal you get a nicer finish.
07-07-2007, 07:28 PM
IIRC the Whipp has a straight cut pinion and bull, these have more of a tendency to give the finish effect you're seeing. Logans had a roller chain drive and had the same thing happen, Atlas's (like mine) had a straight cut gear set and I see it, too. Most of the more "modern" shapers used helical gears, and are quieter, but are more limited in potential repair options. As Ammcoman sez, check the ram gibs, and I find that using the heaviest gear lube you can find both quiets things down and minimizes the ripples. Of course, burnishing is about the toughest task you can do as far as showing us "defects" goes.
Yep, it's a straight cut pinion and bull. You can hear a gentle growl under load so I know it's coming from there. You can feel it in the table too even though I have the support set up fairly tight. I have put very heavy lube on the bull and it might have helped a bit but it still leaves a pattern. I guess that comes with the machine.
I have been doing some more testing and the one thing that is still a crap shoot is setting the tool pressure. Too little and the finish isn't as good. Too much and you stick the tool and ruin the work.
07-07-2007, 10:52 PM
Try a ball bearing as the burnishing tool. The rollers on turret lathe roller turners burnish the surface, may work in your application.
07-07-2007, 11:29 PM
Hmm. Interesting operation. Your burnishing tool looks nice and shiny :) I would imagine that different materials for the tool would change the results, as does the lube used. Have you tried pee, or vinegar- a somewhat serious suggestion. For the tool you could try a chunk of CBN embedded in a holder of some sort.
As far as the pattern that develops, it would seem that the most viscous way lube that you could use on the ram ways would have the most effect to lessen this. I have to guess that it's a vertical variation issue with the meshing of the teeth, and not a speed variation thing. (ram speed and vertical motion)
I wonder if this pattern has become part of the ram and the ways- it would be the result of years of use.
Another take on the burnishing tool- how about a hardened roller? Some experimenting with the width of the roller in contact with the workpiece would be in order. Contact pressures are probably pretty high so the roller and it's bearings would have to be up to it. While on this thought, you could knurl with that setup, though I don't know what the results would be like.
To round out my list of brain farts, there's ultrasonic 'massaging'. Have a transducer mounted to give the tool some jackhammer effect.
07-08-2007, 12:03 AM
My Whipp shaper is producing clear periodic marks that are directly timed to the gear teeth on the bull gear and pinion meshing. This becomes much easier to see with a specular finish. In this pic the effect can be seen as vertical striations in the finish. It can't be felt or otherwise measured with ordinary equipment but on a specular finish any deviation from purely flat is easy to see.
I can't think of any way to alleviate this. Does anyone have any ideas?
Evan, my Rhodes also has the periodic marks. I presume they are due to wear between the bull gear and pinion, and since the pinion is a very small and heavily undercut gear I've been expecting that I'd have to make at least a new pinion gear. I haven't done anything with the machine since I noticed that issue, and I can't recall how evident the patterning was to the fingernail test.
It may be that it serves as a good excuse to try making a gear, on the basis of "it couldn't hurt" to have a fresh pinion.
The patterning in my case can't be felt or measured with machinist tools, only seen. With a specular (mirror like) finish the surface has a peak to valley flatness on a local scale of better than 1/2 wavelength of light, or about 0.00001". Even slight departures from this flatness on average are very visible.
The vibration isn't in the ram and the ram ways are nearly perfect for a machine this age. I had the ram off and checked everything when I repaired the yoke follower. The gibs are adjusted and I am using ISO 68 compressor oil and a bit of STP. This is a pretty lightweight machine for a 16" shaper as it weighs under 1500 lbs. It is somewhat flexible and might benefit from being bolted down to a more rigid surface. I have it sitting on several 1 1/2" blocks of wood to help isolate the noise from the floor and foundation so it doesn't disturb swmbo in the evening.
07-08-2007, 01:03 AM
I was taught to broad noze to get fine finishes. The tool is straight across and set parallel to the work. Depth of cut 0.0010 or so. Feed about 1/2 to 3/4 the tool width. On a large machine like a planer that can run about 1" of cross feed. If the tool is perfectly set and the material cast iron the feed marks look like satin ribbons laid parallel. There's no shingle and the surface has no directional texture.
You can get the same effect on steel and aluminum if you use gooseneck tools and the right coolant.
Broadnozing works on engine lathes too or wherever single point tools can be applied. Here spring tools are used or run the machine in reverse. We used to peel big propeller shafts with spring tools. Towards the finish cuts the chips would come off like metal foil.
This would take very little to set up as a test, but I wonder if it would help control the finish of you were to lash up an automobile or motorcycle type shock absorber to the ram. A fine old British knee action shock absorber would actually look right in place on a machine like that. A very heavy duty shock would probably cause the motor to stall, but for the purpose of testing it may be worth a look.
07-08-2007, 04:46 PM
I was taught to broad noze to get fine finishes. The tool is straight across and set parallel to the work.
Broadnozing works on engine lathes too or wherever single point tools can be applied.
Forrest, for an engine lathe, is that tool truly straight across, or is there a radius to the blade?
If it's straight across, how do you keep the edges from digging into the work?