Compass Cutter Really Sucks!

[medved]

Do all Compass-cutters suck?

Wondering if there are any significant differences in brands & types?
The notion of a bow cutter appeals (esp. as I imagine I could make one.) as its' design suggests it could be more accurate.

My cutter


This cutter has several flaws.
1. Blade height isn’t adjustable – so one has to force the point of the pin through to a depth of about 3mm to make proper blade contact & this really doesn’t help with snagging, tearing or the need to be precise.
2. Measurements aren’t as clear as they might be.
3. Sensitivity of adjustment is poor.

In testing on a scrap piece of paper, an average of 3 of 15 circles were actually ‘circular’, mostly ovals & spirals resulted. I have destroyed some parts on my next project
Stug III
because of this, believing even after so many practice failures I could try to actually cut out something I wanted……The fact that no center point is marked (just a W) didn’t help & the superglue in the centre tip is somewhat nullified by having to force the point through so much.


I see the Olfa deluxe model has some good features – anyone use one?
Anyone modify a standard drawing compass to hold a blade successfully?


I am trying to collect some pipe scraps that can be honed to make ‘larger’ punchs e.g. 15mm copper water pipe seems to be a good idea, but ultimately a punch is less flexible with size than a compass.

Beyond that, who is the circle expert here???

[Keds_Girl_Lala]

I use that very same cutter. Please find my posts on the Traction Engine.

It is best to use with circles some what larger obviously than the smallest setting. I use bees wax on the blade to make it cut more smoothly. And to make the cutting more easy, I stick the needle point deep into a cork board on the back of a trivet to use as a cutting platform.

I use this also if you find my Wilhelmshavener Messerschmitt 109

[buffalowings]

I have TWO olfa circle cutters, I rarely use them though, I prefer to just stap/nip holes into the paper with a knife

[Ron0909]

I have the olfa cutter and have come to the conclusion it sucks as well. Strange...I had one about 4 years back prior to the big 'loss' that seemed to be more accurate and stable. My memory doesn't see any difference in construction but that is an aging memory Anyways, the complaints you have are almost identical to the ones I have. What gets me the most is the bevel each cut circle has. I used to have some blades I believe were made by Grifhold that were meant to go in a bow compass. I never had a suitable compass but I imagine they would have been perfect. I found a pic of what I'm talking about. They were bevel cut cylinders. Not sure if these are the correct size but they look the same.
Ron

[EricGoedkoop]

I have two compass cutters very similar, an Olfa and a C-Line. The Olfa is constructed a little better, but the C-Line will cut a slightly smaller circle. I find them indispensable, though frustrating at times. Some tips:

1) Change the blade as soon as it starts to drag. A dull blade doesn't help anything.

2) Use several light cuts, instead of trying to go all the way through in one heavy pass. Less pressure on the cutter will reduce its tendency to wander off-center.

3) Establish the center point positively first. I like cross-hairs at the center of your circle; score them lightly with a knife, then poke a hole with a pin where the two scores intersect. Set the point of the cutter into this hole.

4) Really set it in there (you already learned this, I think). Cardstock, especially a single layer of it, will not hold that thing in place. I jam the point through the card right into my cutting mat.

5) The dimensions printed on the cutter's beam are pretty useless. I measure the radius of my circle and set the cutter using a steel rule. The point (and blade, if it works out right) will nestle in the engraved markings on the rule, making this part pretty easy. Trying to set the correct radius by matching the cutter to your part is a headache.

6) There's a little wobble in the cutter. Even with the adjustment screw cranked down as tight as it'll go, the cutter will move back and forth a little if you wiggle it. Both of mine do this and have ever since they were brand new - I guess it's just something you have to deal with. I find it isn't a problem as long as you use light passes; if you bear down on the the thing it'll shift under the pressure and give you a spiral.

7) Smaller is harder. Anything under about 1" radius is just going to be hairy. These things weren't designed for precision work at small sizes, but they CAN be made to work.

8) Sometimes it's easier to hold the cutter stationary and rotate the card underneath it. This also reduces your chances of getting a spiral.

Just go slow and treat 'em nice. I'd be lost without mine.

[Astroboy]

My Olfa circle cutter sucks too. So I cut it to pieces and you can see the result. The yellow part with blade is all that is left of the original Olfa.

Bill Kastenmeier

[KCStephens]

You're right, none that I have tried, Olfa or otherwise, work that well but like anything else with a little practice your results will improve.

The biggest thing you can do to get good results is make a series of very light passes, don't try to cut through the paper all in one pass, this is especially true for heavier laminated stocks. One thing that I do (especially with pieces on heavier stock) is to make cuts on both sides of the paper. Cut about half the way through on one side, then flip the paper over to finish the cut.

Another thing that you can do to improve the cutters performance is to and eliminate the movement of the cutter head. I have found that this can be done by placing a thin paper shim strip between the cutter head and the beam.

In order to keep the blades sharp I touch up the edge with a wet stone from time to time. Once I go through the 5 or so blades that come with the cutter I toss the whole thing in the garbage and go get a new one rather than try to find replacement blades. They're pretty cheep and usually by that time the thing is worn out anyway.

It would be nice if some one would design and build one that was made out of metal that used a common #11 blade. I would be willing to pay a few extra dollars for something that was more precise and durable.

[cdavenport]

I like my Olfa circle cutter, but it does have its limitations especially if you are working with thicknesses greater than 1mm.

So, I machined a set of circle punches out of 4140 hardenable steel. I have a wide variety of diameters. You can contact a machine shop and have them to the same for you.

With my Reheat Models hole punch, I can get everything from 1mm up to and including 1.25 inch which seems to satisfy my needs thus far.

[medved]

Thanks for the help everyone. Very much appreciated.

Looks like I'm gonna have to get it out for some more tries using EricGoedkoops' detailed advice!
Some things I hadn't thought of there.

I had been trying to set it against my micrometer, having measured the parts in question.
I had tried to establish the center using a drawing compass but hadn't thought of scoring the +
I definitely saw a wobble & worse when trying to gently cut with multiple passes it really wants to spiral - I had tried to cut out the tyre 'edges' (a 'life-saver' hollow circle @15mm/18mm) & it just chewed them up - if the internal cut went OK the outer would kill it... & vice versa of course


Ron0909 Yes I had seen these there is a bow compass designed for use with them specifically - its available in the US (but I think not in the UK ) but I can't recall the part number. I expect you could trace it via the blade part no. I think they were about $30 though.

KCStephens Talking of good designs - This really looks nice ( I wonder how many tries they had for the advertising pic tho :D ) Rotring if its as good as their pens it would be worth a go......

Lala - I see you have made some very nice wheels with this thing! I will have to try a different 'base' for pushing the pin into. I guess cork is probably the best substance for grip.
(off-topic - I suspect you may like the ЗиС-5 «Фургон» - I found recently, I have put the link in my thread on Kotelnikov)

Astroboy Very nice mod! :D

[medved]

cdavenport So far I'm inclined to whole-heartedly agree & take the punch route but I don't want to give up without a fight!