What's this tool? #3: Circle Cutter

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Blog entry by swirt posted 06-10-2010 04:08 PM 5195 reads 0 times favorited 19 comments Add to Favorites Watch
« Part 2: Wooden Paddles Part 3 of What's this tool? series no next part

Back in my Great Uncle’s Old toolbox (he was a finish carpenter in the 1930’s) I found this odd circle marking / cutting device that is used in a brace.
antique circle cutter
(The tri-square in the photo is 6” long)
The arms are fully adjustable in length from roughly a 1/2” radius out to ~3” So it could mark out a circle out to about 6” in diameter. Given the design, the outer edge of the circle could never be less than ~1 1/2” in radius.

The center post (pivot) has no threads on it and is tapered, so it could fit into a small hole, but could not make the hole deeper (so it is not like a drill).

The ends of the pointed arms are sharpened so it is designed to cut when moving in a circular arc.

I did find a few of these on ebay and they were identified as leather washer cutters. I am not sure if this is accurate or not. It would make sense that it was intended to cut something thin, like leather, because it could not drill deeper on its own. What I haven’t been able to wrap my brain around is why there would be a need for leather washers that large. (who needs a 6” diameter leather washer??) And more importantly why would a finish carpenter in the 1930’s need to make leather washers on the job site?

One idea occurred to me that it may have been intended for making leather washers, but he may have re-purposed it for scribing circles on a surface (like a plaster wall) and then used a compass saw to cut the circle out. Today it could probably cut the hole in drywall with no problem, but in the 1930’s walls were plaster and lathe, which would not cut well with this tool by itself.

Anyone know what big leather washers were used for or have other ideas why this would have been in his toolbox? Thanks in advance for any help provided in working out this little puzzle.

Again anyone interested in old tools can read the rest of my look inside the old carpenter's toolbox.

-- Galootish log blog,

19 comments so far

View JJohnston's profile


1622 posts in 3258 days

#1 posted 06-10-2010 04:49 PM

Pump cups?

-- "A man may conduct himself well in both adversity and good fortune, but if you want to test his character, give him power." - Abraham Lincoln

View Randy Sharp's profile

Randy Sharp

363 posts in 3639 days

#2 posted 06-10-2010 05:05 PM

I’m guessing outside the box, but one thought would be to use them as some type of heat shield around ceiling mounted light fixtures (and the such), where fire hazzards would be a concern. Conventional light kits have insulation and foil for that purpose. In the 30’s, perhaps it was leather?

-- Randy, Tupelo, MS ~ A man who honors his wife will have children who honor their father.

View David Craig's profile

David Craig

2137 posts in 3075 days

#3 posted 06-10-2010 05:41 PM

Leather washers are used for chisel handles and mallet faces. Might have been used to cut leather circles to mount over a mallet face to help prevent marring of the workpiece.


-- There is little that is simple when it comes to making a simple box.

View Gregn's profile


1642 posts in 2950 days

#4 posted 06-10-2010 05:48 PM

I have 2 of my grandfather’s a large and a smaller one. He was a welder/ machinist. The story he told me was this. Back in the good ol’e days remember all the belts and pulleys and levers that were in the shops for powering machines. He said they were used to cut leather and fibers washers as well as light tin for the pulleys and belt system. I guess they use to lather up the leather with grease sometimes to act as a type of bearing deal for parts that slid back and forth. They were also used for pump washers that needed to be replaced. This was the story he told me when I was a kid. Fact or fiction it made sense to me then.

-- I don't make mistakes, I have great learning lessons, Greg

View swirt's profile


2646 posts in 2938 days

#5 posted 06-10-2010 05:53 PM

@JJonhnston Pump cup leathers would seem to be the right size. That would make sense for the tool. I’m not sure how many hand pumps were in use in the 30s in Rochester NY maybe quite a few…. not really sure when municipal water started up there.

@Randy some kind of heat shield might might sense. Though I would think that would be more the job of the electrician. ... not sure how much jobs overlapped back then. There were no wire cutters or anything remotely electrical in the toolbox.

Perhaps scribing holes for metal chimneys? It can scribe concentric circles (2 at a time) or if set to the same size it can scribe one circle twice as fast.

-- Galootish log blog,

View a1Jim's profile


117063 posts in 3544 days

#6 posted 06-10-2010 05:58 PM

My thought was that perhaps a leather washer that size would be for wagon wheels.

-- wood crafting & woodworking classes

View swirt's profile


2646 posts in 2938 days

#7 posted 06-10-2010 05:59 PM

@Gregn – That makes a lot of sense to me. Leather washers all lubed up would probably do the job you describe pretty well.

@David – I thought about that too… Chisel handles or mallet faces made sense at first until I tried scribing some circles and realized that it couldn’t make washers small enough for chisel handles and if it were used for mallet faces they would have a hole right in the middle of the strike zone.

-- Galootish log blog,

View blackcherry's profile


3337 posts in 3789 days

#8 posted 06-10-2010 07:38 PM

Sorry i don’t know to much about the tool in question, but I have the same square in my shop…BC

View uffitze's profile


199 posts in 2922 days

#9 posted 06-10-2010 07:39 PM

I’ve worked on a few old houses, and have yet to see a leather washer of any size in one. I’m a sparky, and have not seen anything like that used as insulation in light fixtures (they didn’t seem to think that insulation was necessary back in the day).

6” is probably too small for a chimney.

Sorry I’m not more help on this one.

View swirt's profile


2646 posts in 2938 days

#10 posted 06-10-2010 07:54 PM

a1Jim, I’ve never seen them but probably wagon washers would be the right size and function the same way Gregn describes. So it would be a good use for the tool.

I guess I keep banging up against the notion that he probably used this tool for something other than it was intended…. I know I have a few tools in my toolbox that serve a different purpose for me than they are originally designed for. (Hmmm maybe I should start leaving notes in my toolbox for the days when my grandkids are puzzling over what I used them for. LOL)

-- Galootish log blog,

View swirt's profile


2646 posts in 2938 days

#11 posted 06-10-2010 08:11 PM

@blackcherry That tri-square was also part of his toolbox. Was yours made by SOHACO – Southington Hardware Co. ? That is the stamp on it. Here is a link to an old Southington catalog from 1930 Funny to look at the prices of the tools. Apparently this tri-square sold new for between $2 and $4 (only because I am not sure which one it is by number).

@uffitze actually you provided some great info. ... no old time leather insulation and chimneys on old stoves were bigger than this would scribe … So I can cross two of the possible uses off the list. It is not the homerun you hit in the other thread with figuring out that the wedges were probably used for hanging doors, but it is useful info just the same.

-- Galootish log blog,

View swirt's profile


2646 posts in 2938 days

#12 posted 06-10-2010 08:13 PM

Scribing holes for toilet toilet drain pipes perhaps?

-- Galootish log blog,

View Gregn's profile


1642 posts in 2950 days

#13 posted 06-10-2010 11:30 PM

I found this link it looks something like you have.
Which would coincide with the story my grandfather told me.

-- I don't make mistakes, I have great learning lessons, Greg

View Dusty56's profile


11819 posts in 3654 days

#14 posted 06-11-2010 02:08 AM

“It’s time to make the doughnuts”

-- I'm absolutely positive that I couldn't be more uncertain!

View canadianchips's profile


2600 posts in 2963 days

#15 posted 06-11-2010 02:58 AM

Back in 30’s the men used to do more than just carpentry. They also did the plumbing, wiring, tinsmithing, et. Sub-trades were not here yet. I believe that tool may have been used to cut washers for hot water radiator systems in homes. (gaskets)
Not that I was here in the 30’s. but THEY SAY !
My grandfather (born in 1896) was the local blacksmith, carpenter,plumber, electrician. “German nickname was Tischler” I was always told that meant ”Jack of all trades

-- "My mission in life - make everyone smile !"

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