Metal Shapers

by Kay Fisher

Shaper Tool Bits

Part 2 of 3

Tool Posts

There are two common shaper tool posts. The English style, which is seldom found on American made shapers, and the American style, commonly referred to as the lantern-style tool post. Each has its advantages and disadvantages.

English-Style Tool Post

English Style Tool Post                               Drawing by Kay Fisher

The English-style tool post, shown above, mounts the tool further back than the American style, putting the cutting edge more in line with the pivot point of the clapper. This helps to eliminate the bounce pattern visible on many shaper finishes, as mentioned by Rudy Kouhoupt in the January/February issue of Home Shop Machinist magazine. The English style is less convenient than the American style for setting up tool angles.

Lantern-Style Tool Posts

The lantern-style post is the most post on shapers. It is also a common on older American lathes. The British call these American-style tool posts. They are an excellent tool post for shapers. They are not popular on lathes because they are awkward for tool height adjustment. On a lathe, height must be adjusted every time a tool bit is changed or sharpened. On a shaper, there is no concept of tool height adjustment. It is just not necessary.

Lantern-style tool Post                                 Drawing by Kay Fisher

Armstrong-Style Tool Holders

These tool holders are useful on shapers particularly if you have a lantern-style tool post. Since lantern-style tool posts are in disfavor for lathes, you can find Armstrong-style tool holders cheap at flea markets and used machinery dealers. They are still popular on larger lathes because they are extremely rigid. New Armstrong-brand tool holders cost from $90 to $220 depending on size. Imported versions cost from $19 to $48. Home-shop shapers hold the smaller size and used or lower-quality holders are just fine for home use. I purchased 3 for $5 from a member of our club at one of our meetings.

Three Smallest Armstrong Style Tool Holders  Photo by Kay Fisher

They come in many sizes. Pictured above are the smallest three sizes #00 at the top, #0 in the middle and #1 at the bottom.

Set of Armstrong Style Tool Holders     Photo by Kay Fisher

A complete set is includes a left, right and straight holder, as shown above.

Armstrong Style Tool Holders
Holder Size Shank Size Bit Size
#1 1/2 x 1 1/16 5/16
#0 3/8 x 7/8 1/4
#00 5/16 x 3/4 3/16

Diamond Tool holder

These are a great invention for the lazy or inept tool grinder (Hey – I resemble that remark). Because of the complex way the tool holder presents the tool there is a need to only grind one surface of the tool bit and they supply a special jig to make that easy.

Diamond Tool Holder                              Photo by Kay Fisher

The disadvantage of this holder for lathe use is that after grinding, you must readjust for center height. Since we are using the tool on a shaper, we are not so concerned with readjustment after grinding.

They are advertised regularly in Machinist’s Workshop and Home Shop

Machinist Magazines and are available from:

Grinding Tool Bit Angles Accurately

In order to consistently grind tool bit angles, you need a stable table for your grinder.

Homemade Table on Old Sears Grinder  Photo by Kay Fisher

Pictured above is the table I made for my old grinder using a scrap aluminum plate bolted to the existing tool rests. Both sides tighten up with wing nuts. I milled slots in the top for a miniature miter gage.

There is an excellent article in the July/August 2003 Issue of The Home Shop Machinist by Steve Wellcome called “Sharpening HHS Lathe Tool Bits. I highly recommend this magazine. Back issues are available. I also recommend their books.

Setting Grinding Table Height                Photo by Kay Fisher

To show details more clearly in these photos, I removed the wheel guard. Based on Steve Wellcome’s article, I set my table to be at the center height of my grinding wheel.

Grinding 7.2 Degrees                              Photo by Kay Fisher

This puts the top of a 3/8” tool 3/8” above the wheel center, giving a clearance angle of , where H is the height above the centerline (in this case 3/8”), R is the radius of the 6 inch grinding wheel (3”) and A is the resulting clearance angle at the tip.

Grinding 14.5 Degrees                            Photo by Kay Fisher

To grind 14 degrees, put a spare 3/8” tool blank under the 3/8” tool bit.

Grinding 12.0 Degrees                            Photo by Kay Fisher

To grind 12 degrees, put a spare ¼” tool blank under the 3/8” tool bit.

Grinding a Right Knife Tool

I made a miter gage for my grinder out of scraps. The picture below shows the gage with the finished right knife tool on it. The only unique feature of this miter gage is a 3/8” high slot in the front of the miter. This allows me to stack a 3/8” tool bit on top, giving a 14 degree angle on the top edge of the tool bit.

Miter Gage                                              Photo by Kay Fisher

I use a protractor to set the miter gage for the 7 degree relief angle, as shown below.

Setting Miter Gage to 7 Degrees          Photo by Kay Fisher

This angle defines this tool style. To facilitate grinding this angle, I mounted a 1-2-3 block on the miter gage. Because my table is aligned with the center of the wheel, this also grinds in front clearance.

Grinding Relief and Front Clearance     Photo by Kay Fisher

Front clearance and relief are easy to grind. Mounting the table at center height while grinding a 3/8” tool bit sets the clearance to 7 degrees. Setting the miter gage for 7 degrees sets the relief angle required for a knife style tool.

Grinding Side Clearance                         Photo by Kay Fisher

Side clearance is simple using the miter gage to hold the tool straight. The 7 degrees angle comes from the position of the top of the tool over the wheel center line.

Setting Miter Gage to 14 Degrees         Photo by Kay Fisher

The compound angle of top and side rake on the top of the tool is slightly harder to set. Top rake comes from setting the miter gage to 14 degrees with a protractor.

Grinding Top and Side Rake                   Photo by Kay Fisher

Side rake comes from raising the tool by mounting it on the 3/8” ledge of the miter gage. When completed, the tool has a compound rake angle as shown below. It can be used for both cutting down and right.

Right Knife Tool Completed                   Photo by Kay Fisher

Special Tool Holders

The two tool holders in the top of the below picture have a small dimple and ram nut that sets them up as a left, right, or straight holder. They are actually lathe threading tools but work well as shaper tools. Unfortunately, they have no built in rake and have the cutting bit further forward than I like.

Special Tool Holders                               Photo by Kay Fisher

The shaper tool holder on the bottom of the photo is continuously variable in angle and holds the tool with built in rake. Also, it holds the tool bit further back to line up closer to the pivot pin of the clapper box. It is my favorite of the special shaper tool holders. This one was made by the Colton Comb Tool Co. of Easthampton Massachusetts. I got them free from friends or for less than 5 dollars at swap meets in New England. Today this type of shaper tool holder sells for more than $70 on eBay. They aren’t very complex. You could easily make one. There are good plans available on-line in the Yahoo group “Metal_Shapers” file section. The file name is holder1.jpg and it was designed and submitted by Art Voltz, a frequent contributor to the group and to this column.

The problem with all tool holders is that each mating surface decreases rigidity. Just mounting a tool bit in the tool post gives the best rigidity and the least chatter and flexing. In the photo above you see a very large tool bit (3/8” wide and 1” deep) mounted in the tool post.


With all this in mind I suggest the following:

  1. Always examine your chips and finish quality. If the chips don’t curl off nicely or the finish looks rough, regrind and hone your tool bit.
  2. Try a special shaper, Armstrong-style or diamond tool holder. See if you like it.
  3. Don’t take tool bits too seriously. Eventually you will find 4 favorite bits that will work for nearly everything.

Good Shaper Tool Holder                       Photo by Kay Fisher

Large Tool Bit in Tool Post                     Photo by Kay Fisher

Next month, in part 3, we will get an expert’s contribution on the shearing tool – a tool with a special angle that has particular application to shapers.

Keep sending me email with questions and interesting shaper stories.

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