screw type help

[Ralph Boumenot]

I am hoping that someone on the creek can answer this question for me. I have a Stanley Victor #20 compass plane and a short round flat head screw holds the frog in place. Whoever owned it before me had it set for a fairly wide open mouth and I want to close it up. The problem is that is almost impossible to get a screwdriver in there to tighten and loosen the screw.
I've got it apart now and I thought I was being clever and I would replace the screw with a bolt and use a wrench to tighten it. Now for the problem.
This screw isn't a standard size. I thought it might have been a 1/4-20 but it isn't. It's about the size of 1/4 screw and the threads are 20 (checked with a screw pitch gauge) but it will not thread into either of my 1/4-20 screw check gauges. I'm not a machinist and I am not familiar with to me are strange sized screws. Any ideas on what the size of this might be?
thanx
ralph

[Hilton Ralphs]

Are you sure it's not 1/4-28 UNF? I ask because the Stanley No 80 Scraper requires this obsolete screw.

[george wilson]

I can make any screw. PM me if you want me to.

[Jim Koepke]

Most likely it is a 12-20 thread. This was commonly used on Stanley planes.

Are you sure the mouth is adjustable on the #20?

My experience with the #113 gave me fits until the proper chip breaker and lever cap were obtained.

Here is information from the source:

http://www.supertool.com/StanleyBG/stan3.htm#num20

The #20 also has a chip breaker that is unique.

jtk

[Dave Sheldrake]

1/4 20 BSF?

Pitch and diam sound right UNF and UNC are truncated form 60 degree, BSF is full form 55 degree.

cheers

Dave

[Mel Miller]

I don't think the mouth on a 20 is meant to be adjustable. The screw that holds the frog in place is just for that purpose. A right angle screwdriver will lock the screw tight after you let the frog slide down as far as possible to where it is supported by the main casting.

[Bill Houghton]

Are you sure it's not 1/4-28 UNF? I ask because the Stanley No 80 Scraper requires this obsolete screw.

1/4" - 28 is NOT an obsolete type. Any good hardware store would have it.

But many of the Stanley screws are, indeed, what are technically called "special" threads.

[Jim Koepke]

1/4" - 28 is NOT an obsolete type. Any good hardware store would have it.

But many of the Stanley screws are, indeed, what are technically called "special" threads.

Next time you are in a good hardware store look for a 1/4-28 fastener.

A lot of my time has been spent looking in some very good hardware stores that do not carry it.

jtk

[george wilson]

thd. is the standard fine 1/4" thread. However,there may be some special diameter that Stanley used. I'm not a Stanley expert,but if I had the part it went into,I could make a screw to fit it. No biggie with a lathe.

[Bill Houghton]

Next time you are in a good hardware store look for a 1/4-28 fastener.

A lot of my time has been spent looking in some very good hardware stores that do not carry it.

jtk
I guess I'm just lucky; my local Ace hardware has all the National Fine sizes up to about 1/2". Sorry to hear that's not true everywhere.

Now, square-headed bolts, that's another matter.

[Hilton Ralphs]

1/4" - 28 is NOT an obsolete type. Any good hardware store would have it.


Is it Metric? :)

Just going by the screw types offered over at Lee Valley, they only reference 1/4-20 screws UNC. So I figured this was not that common any more.

[Ralph Boumenot]

You move the frog up and down on a slot and this opens and closes the mouth. I should have left it alone but I didn't like how much the mouth was open.

[Ralph Boumenot]

It's not a 1/4-28. I tried it in every 1/4 hole in the guide. The size is the same the threads don't match up.

[Ralph Boumenot]

It's impossible to get a rt angle screwdriver in there 90 to the head. At least every one I have won't do it - they are all too big.

[Ralph Boumenot]

I don't think it's BSF as I can't imagine Stanley using something British in the States. My screw pitch gauge is dead nuts on 20 TPI and it looks to be a coarse thread.

[don wilwol]

this may end up a double post but here goes. Its probably a 12-20 thread. I've posted a list of some common threads Stanley and some others used here, http://lumberjocks.com/donwilwol/blog/24090 They are not common but a tap and die set can be purchased here, http://stjamesbaytoolco.com/ just look for the 12/20 Tap And Die Set $35.00

[Jim Koepke]

Is it Metric? :)

Just going by the screw types offered over at Lee Valley, they only reference 1/4-20 screws UNC. So I figured this was not that common any more.

Not likely metric on a Stanley plane.

Years ago when living in the San Francisco area I searched many sources for 1/4-28 fasteners. They were not even listed on line at the time. Maybe things have changed. A few sources are now found on line. I still haven't found any locally even at the local specialty stores for fasteners. They mostly only carry what the local industry is using.

Recently discovered the difficulty of obtaining 5/8" carriage bolts to mount my vise. Could have ordered them in town if I was willing to buy 1,000. Ordered from McMaster-Carr and only had to purchase lots of 10 except the flat washer was a minimum lot of 50.

jtk

[Greg Wease]

Most Stanley frog screws are #12-20 (before they went metric). The size was established in the 1850's when 12-20 was apparently a standard size and Stanley never saw a reason to change.

The screw in the #20 plane is a bit larger--see later posts for size.

[Jim Koepke]

In rereading this thread with this morning's SMC Data Base problem the OP (Ralph Boumenot) is not in need of a new fastener as much as he needs to reinstall the original fastener.

From looking at a few images of this plane my guess is the link between the sole and the plane body is getting in the way of making the installation.

It may be necessary to remove the pin attaching the link to the sole in order to have a clear shot at replacing the original screw.

If there isn't enough room to get an angled screwdriver in to do the work, there likely isn't going to be enough room to insert a wrench to tighten a cap screw or other fastener.

It is at best difficult to direct a course of action from a remote location.

Often it is possible to start a screw in such a tight area with a small driver and some tape. Once the fastener is close to home it may be possible to give it the last bit of turning with a proper sized driver.

Note: Just found an image on line showing the screw location. It appears this is a difficult place to get into with a screw driver. Most likely the frog is attached to the main body before the sole is attached. Flexing the sole to its full concave position (for working the edge of a circle) may give a little more room.

Not sure where you might find one, but General Tools used to make a very low profile ratcheting 90º screw driver that might fit into this area.

jtk

[Roger Davis IN]

Just checked my #20. You've got the pitch right at 20 tpi, but the diameter measured 0.260-0.262 inch (not so round). A 1/4-20 screw will thread happily into the hole, but it is unusably sloppy. By the formula for numbered screw diameters, it's about a #15.5! I looked through several very old references, and #14 was the biggest one I could find specs for, although a Wikipedia article did note the existence of #16 machine screws.

Using an old Yankee ratchet offset screwdriver, I could easily reach in and loosen the screw. The upper part of the frog that this screw secures DOES NOT adjust the mouth opening. The lower part of the frog is the casting that the curvature adjusting screw mounts to and is fixed to a dovetail-shaped block immovably riveted to the sole and which forms the back of the throat. The upper part of the frog carries the depth of cut and lateral adjusters and has the screw for the lever cap. Making the frog in two pieces was almost certainly done to make machining easier/possible. The face of the upper frog lies in the same plane as the throat surface of the dovetail block, and the screw and slot are for assembly only, not adjustment. The screw bottoms out in the slot just before the upper frog runs into the dovetail block on my plane. You are not going to find a replacement for the screw in any hardware store, but it also will not allow any adjustment of the throat opening.

[Dave Sheldrake]

Full form or truncated Ralph?

cheers

Dave

[Greg Wease]

Just checked my #20. You've got the pitch right at 20 tpi, but the diameter measured 0.260-0.262 inch (not so round). A 1/4-20 screw will thread happily into the hole, but it is unusably sloppy. By the formula for numbered screw diameters, it's about a #15.5! I looked through several very old references, and #14 was the biggest one I could find specs for, although a Wikipedia article did note the existence of #16 machine screws.

Using an old Yankee ratchet offset screwdriver, I could easily reach in and loosen the screw.

I had never disassembled my old #20 1/2 (old enough to be labeled "Victor" on the adjustment knob) until now. I was wrong, it isn't a 12-20 (I'll have to update my previous reply). The diameter of my screw is a little smaller than Roger's; it measures 0.254" and 20 tpi. The threads are a bit flattened so I don't know the original diameter.

I cranked the sole of the plane fully concave and was easily able to reach the screw to remove and replace it using a standard slotted screwdriver. Ralph, have you tried this?

As Roger points out, this screw isn't for adjustment, only for assembly.

[Mel Miller]

This thread has gotten way too confusing. OP has the correct screw, but incorrectly thought it was used for adjusting the throat. Now, since that idea has been disproved, all he needs to do is put the original screw back in, tighten it up and leave it alone. It's easy to start the screw with the frog out of the plane, then slide the frog into place and tighten the screw with the screwdriver of your choice.

[Winton Applegate]

Sorry, couldn't pass that up.

Like George I pounce on any excuse to use my metal lathe but . . .


http://www.amazon.com/4-28x5-Socket-Button-Screw-Finish/dp/B00CH76OCW/ref=sr_1_4?ie=UTF8&qid=1380597360&sr=8-4&keywords=1%2F4+28+screw


http://www.amazon.com/4-28x7-Grade-Screw-Alloy-Steel/dp/B00AQN2FXQ/ref=sr_1_10?ie=UTF8&qid=1380597360&sr=8-10&keywords=1%2F4+28+screw