Bow Compass Circle Cutter

Discussion in 'Tools of the Trade' started by Gil, Apr 5, 2004.

  1. Gil

    Gil Active Member

    Good Day All,

    I've taken another Total Distraction Disorder Detour once again....,

    Many postings over time have dealt with problems cutting circles accurately in paper. Some of the replies boarder on a Zen Master's dialogue with a Novitiate...., "take a deep breath, exhale, now breath normally while forming a mental picture of leaves floating on the water of a small stream. Now hold that vision while rotating the paper while at the same time working the scissors around the edge of the circle. Not too fast, not too slow, now there, that's just right.....,". Ok, so I'm overdoing it a little but those looking for answers are just told to go practice with their scissors or imagination, whichever works first. I usually have to print out at least a half dozen or so of small circular objects just to get one to come out right (sound familiar?).

    Much time has been spent deriving hole drills and searching for better solutions. Hole drills work well for small diameter circles but become difficult to center on larger diameters. Larger diameters can be handled with the Olfa circle cutter which works from around 0.5" (~1.2cm) to 6" (~15 cm). There is a region between these two methods which, unfortunately, most of the circular cuts seem to fall. A kind of "no circle land". One workable, but limited solution is the leather hole punch which allows holes to be punched in diameters from 1 to 4.5 mm. Once outside this inner domain the solutions become rather dicey. A large hole drill will, after a few tries, yield a passable solution (I thought this would improve with practice, it didn't). A better solution is to use what is called a disc cutter in the jewelry trade and can cut holes from a few millimeters to about 25. The problem with disc cutters is that the top "guide" is made out of plate steel and makes positioning difficult although not impossible. Sighting down through the guide barrel allows postitioning the paper underneath until it lines up with the outside diameter. Insert the die and punch out the circle. Make sure the paper remains clamped in position while punching (which can be problematic). A solution is to replace the steel guide with clear plexiglass much like the Waldron punches which have been discussed in other threads. Disc cutters run around $50 U.S. without modification which is rather steep for the average card modeler.

    I am experimenting with using a 5-inch bow compass with a small razor sharp blade in place of the pencil lead. The first experiment used an Xacto #251 blade (a very small blade used by to cut film by graphics artists). This was silver soldered to a .0625' brass tube so that it could be mounted in place of the pencil lead. A certain amount of experimenting was required to find the best cutting position. Next is to forge the blade out of a suitable piece of piano wire with the right diameter to replace the original eperimental blade setup. I plan to shape the edge into a curve to allow better tracking for the smaller diameter cuts. As usual, pictures if it's sucessful, words if it's not.

    The experimental setup was sucessful in cutting out concentric circles with resulting rings of 1.5 mm between ID and OD.

    Best regards, Gil
  2. Gil

    Gil Active Member

    Bow Compass Forged Cutting Edge

    Good Day Two All,

    It's all in the picture...., It cuts fairly well. It needs a little precise edge grinding and a final stropped edge. Might work after all.

    Best regards, Gil

    P.S. Has anyone seen cutting edges for Bow Compasses? I think they were at one time.
  3. ButchPrice

    ButchPrice Member

    Great Idea

    Great idea Gil !
    I thought about trying something similar.
    I would definately like a better method of
    accurate repeatable circle cutting.

  4. Bikerpete

    Bikerpete Member

    Good stuff Gil. I'm playing with some hole cutting ideas myself but so far have nothing worth posting. One simple thing that would definitely help with all circle cutting would be for the manufacturers to print the centers on the paper. This is a pet peeve of mine but how much trouble is it to print a small cross-hair on the paper? They probably used a center to design the part in the first place.
  5. Ron

    Ron Member

  6. I've got one at work I use for cutting gaskets to close toerences to fit around machine parts. Basically I took a compass and tapped the end where the pencil goes in to the size thread on the end of a #11s collet chuck. 10-24 if memory serves. Works pretty good, or did I "lent" it out. :evil:
  7. Gil

    Gil Active Member


    I tried the Grifhold blade solution and found that they work well with thin paper and films but are problematic with card stock. Keeping the bow centered is where most of the problem lies. The compass I was using had a center with a very small needle for holdng the tool on center...., much to weak for the purpose of cutting card stock. A piece of piano wire stock was ground to a point (similar to that on the Olfa circle) and used as the tools center instead. The performance is rather suprising considering the small amount of time spent on the modifications. It can literally run rings around the competition! The blade and point were both made out of the same piano wire using Dremel cutoff wheels, grinding wheels, sanding drums and buffing wheels for final honing of the blade (which was heat treated to obtain and maintain a sharp edge). One other point is that the blade must be carefully aligned to cut properly (just a little inside of being tangent to the circle cut ("toe-in")).

    Another technique that works well is to "tack" down the bottom side of the paper to a backing surface with the Uhu tack cement (adhesion similar to a postit note) before beginning the cut. This holds the piece in postion after it has been cut through and allows successive cuts to be made either inside or outside of the original without losing the center (all circle cutting work was done on top of an expendable surface such as old magazines).

    Best regards, Gil
  8. Jim Krauzlis

    Jim Krauzlis Active Member

    Great thread, Gil!
    Where does one get those grifhold blades you and Ron mentioned?
    So, you found the modified piano wire worked best for the center point and the blade? Cool!
    What would be the type of cement available in the US similar to the UHU tack cement, if there is any? Not being all that familiar with UHU products (although from what I have seen it must be good stuff since lots of folks swear by it) is it sprayed on or applied like any other tube glue?
    Sorry for all the questions, but your idea is intriguing!
    Good stuff!!
  9. Gil

    Gil Active Member

  10. rickstef

    rickstef Guest


    most craft stores have a gluestick or spray of the postit note glue.

    another idea is to use those post it note bulletin board sheets, they are about the size of posterboard, and they are covered with this glue, and it acts the same way

  11. Jim Krauzlis

    Jim Krauzlis Active Member

    Thanks Rick and Gil!
    Guess I need to venture out to my local craft store more often, I hadn't noticed the tack glue and I just had a need for something like that to temporarily hold a piece. I ended up using a bit of double side tape that is designed to provide a temporary hold without damage to the paper put out by 3M. Always looking out to see what's out there; in case the need arises it's good to know what's available. :wink:
    Have a Happy Holiday to all! :D
  12. Gil

    Gil Active Member

    Low Cost Punch Sets

    Hi All,

    Found some low cost punch items on Harbor Freights website. Two sets of leather punches from 0.1 to 0.319 inch and one precision disc cutter from 0.125 to .75 inch. One other item that you shouldn't be without is the 6 inch digital caliper....,


    P.S. The bow cutter works better than I ever anticipated for circles outside small diameters where the leather punch type tools are most effective.
  13. rickstef

    rickstef Guest

    you guys might want to check out American Science Surplus, they have a Leather hole punch for the amazingly low price of $3.75

    I have one on order, courtesy of my mom, I love Mom.

  14. Gil

    Gil Active Member

    Good Evening All,

    Alene's makes a "stay tacky" glue for the purpose of holding cut circles. An even easier way is to use a postit note sticky side up as a backing before beginning the cut. once done the pieces can be easily pealed off without too much trouble.

    Best, Gil
  15. Ajax

    Ajax Member

    After struggling for 45 minutes :shock: to create a smooth circle that was 1/8" in diameter, I've found this thread very interesting! :D

    Thanks for the link, Rick! I'm definitely thinking about buying one from them. Has it worked well for you in producing nicely shaped circular slugs?

  16. rickstef

    rickstef Guest

    yeah, i have to reposition it only once to get thru, but it works, and then a little trim if there is any hair(fibers) showing
  17. Ajax

    Ajax Member

    Thanks again, Rick! Looks like I'll be purchasing one then. :D


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