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Carter Forstner Extension

Emiliano Achaval

Emiliano Achaval

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I got the Carter Forstner bits extension tool. I'm having a problem with it. The hole for the Forstner shaft is bigger than any of my bits. There is a set screw on one side. When you tighten it, it pushes the bit way off center. I tried a shim, but still, no luck centering it. I wonder if there are any big shaft Forstner. Am I looking at this the wrong way? What am I missing here? Any insights on this tool would be greatly appreciated. I might be having a momentary lapse of reason here. Do not feel bad if you have a solution so easy that you are embarrassed to tell me. LOL
 

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Dave Delo said:
My Carter extension accepts the 3/8" (.375) shaft Forstner bits without issue.
Click to expand...
Thank you for your reply. Maybe I'm missing the right piece, the one that has the 3/8 hole? I contacted someone that works with Carter. I know I'll be hearing from him, but he is traveling to Waco right now.
 
Emilliano, I believe you are correct about the missing piece. It looks like there are two sizes, 3/8th and 1/2. Interestingly enough, from their website, it looks like you can buy extra extensions to lengthen, but not the individual 3/8th or 1/2 inch bit holder.
I love the patina on your bench, I wish we could buy that in a bottle...

Strongbore™ Modular Boring System | Turning Tools and Accessories | Carter Products

carterproducts.com carterproducts.com
 
Emiliano Achaval said:
I got the Carter Forstner bits extension tool. I'm having a problem with it. The hole for the Forstner shaft is bigger than any of my bits. There is a set screw on one side. When you tighten it, it pushes the bit way off center. I tried a shim, but still, no luck centering it. I wonder if there are any big shaft Forstner. Am I looking at this the wrong way? What am I missing here? Any insights on this tool would be greatly appreciated. I might be having a momentary lapse of reason here. Do not feel bad if you have a solution so easy that you are embarrassed to tell me. LOL
Click to expand...
You might ask Carter if they offer a collet insert to fit your forstner bit shaft diameter. If they don't, you might be able to source one at a big box that will securely center your bits in the extension shaft hole.
 
I don't believe your missing any parts. Per your photo, each extension has 1 set screw and the receiver extension of the forstner bit has two set screws. (Looks like you have it according to your pic. My opinion is either the hole has been drilled to large or you are using a forstner bit that doesn't have a .375 shaft. Here's pic of mine with .375 shaft.

After posting..........I see they offer this with 1/2" receiver extension (didn't know that) and looks like that's what you have. Get a .375 receiver or 1/2" shaft forstner bit.
carter 1.jpg
 
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Emiliano Achaval said:
I got the Carter Forstner bits extension tool. I'm having a problem with it. The hole for the Forstner shaft is bigger than any of my bits. There is a set screw on one side. When you tighten it, it pushes the bit way off center. I tried a shim, but still, no luck centering it. I wonder if there are any big shaft Forstner. Am I looking at this the wrong way? What am I missing here? Any insights on this tool would be greatly appreciated. I might be having a momentary lapse of reason here. Do not feel bad if you have a solution so easy that you are embarrassed to tell me. LOL
Click to expand...
It looks like you are missing a piece. Hopefully Carter will confirm. Possible temp fix would be to insert a sleeve of copper tubing or plastic if you can find one of matching diameters. Outside could be turned and inside drilled.
 
So here is a 3-1/8th” Fostner with a 1/2” shank.

This is what I’m working on for a deep bore, no clue if it’s going to work. I’m hoping to hit oil by the middle of next month. My thought is to bore the center using a gun drill, then follow that bore with the shop made counter bore Fostner. Talk about shade tree mechanic…

The pics show the direction I’m headed. The pipe (seamless) OD is 1” , ID 13/16, as is the main shank of the Fostner. The pipe will be cut to a “fork” that slides past the bit, onto the shank leaving an inch or two “nose” protruding, hopefully, to follow the previously drilled 1” bore. Sticking point now is, is welding the best option or the only option for attaching pipe to Fostner?

Fostner, pre-counter bore.jpegFostner, mock up.jpeg
 
I have a couple of the Grizzly H5982 Forstner Bits in the 2-3 inch range that are 1/2" hex.

I received a Carter #2 MT Extension Set when they were first available. The taper appeared to be machined w/o grinding. When it was seated in the tailstock, I could remove it by hand, just grabbing it by the short extension. A replacement set exhibited the same characteristics. Craft Supply said they seated w/o problems in their 7 lathes. I returned both sets.
 
Tom, I've always wanted a metal lathe... but that's probably a whole nuther habit hole...
As for TIG welding, I know a guy who customizes bikes, haven't asked him yet, but maybe he TIG's...
In wood, the gun drill drills slightly oversized so I'm hoping that will help with any misalignment.
I also believe the nose does not have to be very long, an inch maybe, which should also help...
Still playing/figuring/experimenting. Cutting and fitting the pipe this weekend.
 
Don Wattenhofer said:
Long before they started calling that type bit a Forstner there were what were called multi spur bits sold and manufactured in the USA and they all had 1/2" shanks.
Click to expand...
Actually Forstner bits were bits that had the Forstner brand name on the shank. They first were made for the stair building trade when men used the brace and bit. They later came with 1/2" shanks. The multi-spur came afterwords and was a better wood boring bit for machine boring. I've got some older Forstner bits maybe I'll try to get some shots of later on. Today's bits that get called Forstner are good bits for today's home hobbiest grade drill presses that have a very short throw and weak chucks.

Below is an actual Forstner bit from the brace and bit days. The photo was taken for other reasons so that's why the cross tie boring bit is there.
1 forstner a - 1.jpg

Below is my rack of daily user wood-boring bits. Many multi spur bits but several Forstner bits that have the Forstner name on the shank.

1 forstner - 1.jpg
 
Tom De Winter said:
@Clifton C Interesting idea. I would start with tubing slightly oversize. TIG weld it to the bit and true it up on a metal lathe.
Click to expand...

That seems like a very sound strategy. The key to performance will be where the guide meets the cutter. The turning will have to go below the edges of the cutting lips. It may be that the bit will have to be faced first to accept the guide.
Having a friend with a metal lathe will be handy for this project.
"a whole nuther habit hole" is right. Let someone else focus on that commitment of resources.
 
Bob Vaughan said:
Actually Forstner bits were bits that had the Forstner brand name on the shank. They first were made for the stair building trade when men used the brace and bit. They later came with 1/2" shanks. The multi-spur came afterwords and was a better wood boring bit for machine boring. I've got some older Forstner bits maybe I'll try to get some shots of later on. Today's bits that get called Forstner are good bits for today's home hobbiest grade drill presses that have a very short throw and weak chucks.

Below is an actual Forstner bit from the brace and bit days. The photo was taken for other reasons so that's why the cross tie boring bit is there.
View attachment 46144

Below is my rack of daily user wood-boring bits. Many multi spur bits but several Forstner bits that have the Forstner name on the shank.

View attachment 46143
Click to expand...
You made my day. I can now show my wife that I do not have enough Forstner bits, LOL Where is the best place to buy a 1/2 in Forstner? Thank you for your help.
 
Emiliano Achaval said:
Where is the best place to buy a 1/2 in Forstner? Thank you for your help.
Click to expand...
Truthfully, I have no earthly idea. To me, the word "Forstner" means what the original design was: A two lipped bit that was usually guided by a slick outer diameter that drills an almost flat bottomed hole. What gets called "Forstner" in the shiny cheap thing catalogs is more a hybrid of a multi spur bit and an original Forstner design. I've found that this newer design can really do a nice job once well sharpened but durability is limited. If I had to find a special size bit, I'd first go to places that supply the professional woodworking industry like pattern shop suppliers.

In today's world of industrial tooling, the woodworking industry is an unwanted step child. For some amusement, here's one page of many pages of wood boring tooling from an old catalog of woodworking equipment and tooling.
1 forstner b - 1.jpg
 
FORSTNER
Conn. Valley Mfg. Co.
New Britain CT
1874 - 1983
That's what was stamped on the shanks of the original Forstner bits. Quite a bit different from what gets called a Forstner bit today.
They were great for making smooth sided, shallow, flat bottomed holes in wood.

1 forstner c - 1.jpg 1 forstner c - 2.jpg 1 forstner c - 3.jpg 1 forstner c - 4.jpg
 
I had a set of the original Forstner bits back in the 1970s. Not sure where they went, but back then owning two shops with fifteen employees things sometimes happened.
 
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