how to make a circular cut in gasket material

[larryq]

I have to cut special-fit gasket for a small blower motor. I can't find one pre-made for this unit.

I have the gasket material coming in (1/8" thickness) but I need to make a circle about 4 inches in diameter, and no special tools at hand, an exacto knife and that's about it.

The fit doesn't have to be micrometer precise but I'd like to do as good a job as possible and wondered if there were any tips/tricks for doing this?

 

[Sychotix57]

I have to cut special-fit gasket for a small blower motor. I can't find one pre-made for this unit.

I have the gasket material coming in (1/8" thickness) but I need to make a circle about 4 inches in diameter, and no special tools at hand, an exacto knife and that's about it.

The fit doesn't have to be micrometer precise but I'd like to do as good a job as possible and wondered if there were any tips/tricks for doing this?

Can you lay the gasket over the part and tap the edges with a ball peen hammer? That's how I cut my gaskets.

Sent from my Pixel XL using Tapatalk

 

[95vette]

Hello, Use a compass to draw a perfect circle the right size and cut carefully with your knife or a set of tin snips.

 

[jake00]

Holesaw?

 

[Goobzilla]

Compass style cutters can be fairly inexpensive.

 

[phoenix5x]

Got anything round with a 4" OD. Then use a hammer of sorts to punch out the material

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[bwringer]

String, thumbtack, x-acto.

 

[Stuart in MN]

Dime store compass. Take out the pencil and stick your X-Acto knife in it, cut the circle, done.

 

[larryq]

Some excellent ideas here, thanks everyone!

 

[wasfuzz]

find a can, container etc the right dia. and use it a guide if you have to.

 

[RVDan]

Wander your neighborhood in the evening until you find someone tinkering in their garage. Introduce yourself and ask if they have any ideas how to cut the gasket for you. They'll likely do it for you and give you a beer.

Or shoot you the second you step in their driveway depending where you live.

 

[gungatim]

Dime store compass. Take out the pencil and stick your X-Acto knife in it, cut the circle, done.

this.

have done it myself, but use a good compass from the woodworking section at a hardware store, the cheap dime store compass' ****...

 

[wssix99]

Here's the **** Retentive Carpenter's Method:

- Sandwich the gasket material between two pieces of wood, securing all together with fasteners outside of the circle, and securely all around the perimeter - so the gasket material doesn't tear in the next step.
- Clamp the assembly to a drill press table.
- Use a hole saw to cut the center out of the piece.
- Use a larger hole saw to cut a larger ring (and your final gasket) out of the piece.

- Sand the edges, and make it tidy.


I've used this method for solid rings of other material, but would think the secret for this would be how well one could make the sandwich so the gasket material doesn't gear when being sawed.

 

[driftpin]

As others have mentioned, the compass and X-acto knife, or a good pair of shears/scissors. I've done this whenever I didn't have access to the exact gasket. If you have to punch holes for perimeter fasteners, be sure to leave plenty of material to ensure a leak-proof seal. In my experience, investing in a good set of punches to cut your holes is better than trying to drill holes in gasket material. The punch pliers might work for thin gasket material, but I would use a dedicated individual punch for any material w/thickness. Also, cork is very prone to tear easily, should you be using that.

If you wanted to trim the overlapping gasket material once the install is done, an X-acto knife around the perimeter should take care of things nicely.

 

[Falcon67]

>- Use a hole saw to cut the center out of the piece.

a 4" hole saw will cost about 400 times what the material cost LOL. See if you can find a piece of plastic pipe with is the right size. File one end to sharpen. Lay gasket material on a piece of lumber. Back plastic pipe with a section of 2x4. One good blow with a 2 lb hammer.

Alternately, drop by a truck repair shop and ask if they have any cutoff pieces of exhaust pipe around 4" in size.

 

[wayne55]

Scissors?

 

[GreyOwl]

^^^ Or even tin snips.

 

[BearsFan315]

Made a plenty of gaskets for my 1929 i am restoring, actually make most of them if i can. various materials, various thickness. 1/8" thickness of what ?? cork, fiber, rubber ??

1/8" you can cut a pretty good circle with a steady hand and an x-acto. i do 90% via freehand. i did buy a hole punch set to punch out all the bolt holes i also use nice heavy duty scissors to cut the thinner material. i make sure i DO NOT fold the material. many say fold it in half and cut out the circle. this can create a leak path or damage the gasket.

i also digitize all the gaskets i make, so that when i need a new one, i can print out a pattern, lay it over material and cut a new one.

 

[JABgj]

You can build your own compass out of a 1X2 piece of pine. Drill a small hole at one end of the wood for a finish nail and push the nail thru for the pivot. Drill another hole for the Xacto knife with the center of that hole half of the diameter of the size you need. The
board will lay flat on top of the material and give stability. Practice on a piece of chip board first to get the feel and verify the size. Easy peasy.

 

[Ditch]

use a piece of pipe as a punch
Sharpen the edge and use a press or hammer.
Preferably a press.

I have a set of punches for making gaskets but nothing that big.

 

[kbs2244]

You don't say what the material is made of.
Any non-metal material I use a scissors or your e-xco
Metal is tin snips time.

 

[6768rogues]

I agree with the guy who said to hammer it out. Just did it last week.

 

[CN Spots]

Use the Xacto knife (if it's soft material). This is a job it excels at. If it's sticky material like rubber or cork, don't pull the blade like you're cutting carpet... put the gasket material on a few pieces of cardboard and push straight down through it. Think tiny jig saw motions. You'll be done in no time.

And cut the big hole first. Nothing worse than trying to cut something like that out with nothing to hold onto.

 

[bob15]

Mayhew hollow punch set: http://mayhew.com/hollow-punch-sets/

or a leather punch or a razor blade

 

[Marctrees]

Does it have to be made from sheet material?

Silicone RTV caulk neatly applied not work?

Just askin.

Otherwise, since you need just one, I would do the compass, sharp fresh exacto, light cuts in succession, and time.

After the compass lines, maybe glue the inside scrap part to a piece of plywood, drill tiny hole where compass needle was, pound through finish nail into workbench, .

Then rather than moving your cutting hand, think more about slowly spinning the ply piece slowly while you stay on line.

Shallow cut, new blade, keep goin round few times, will look Factory.

And most importantly - Watch where you place your hands if that knife should slip.

If I had one of those butcher gloves w the mesh, I would wear that on my hold down hand. Marc

 

[Marctrees]

More brainstorm food --

https://www.google.com/search?q=cut...TCYKHWxzBAcQ_AUICygC&biw=1280&bih=906#imgrc=_

 

[Ditch]

why are so many so set on hand jobbing the gasket?
Punching the hole is so much easier.

 

[wssix99]

>- Use a hole saw to cut the center out of the piece.

a 4" hole saw will cost about 400 times what the material cost LOL.

Cost is no object to the **** Retentive Carpenter...

 

[ArkTinkerer]

If possible to do smaller holes to align the gasket on the part, often you can run the knife along the edges of the part for larger cutouts and the outside.