Best way to flatten cupped grip

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Last Post 01 February 2022
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CBA Member

GBertolet posted this 26 January 2022

I recently purchase replacement grips for an old Spanish 6.35 auto. One of the grip panels is cupped. It's wood, and I am asking for the best way to flatten it, to be even with the frame. Should I soak it in water, steam it, or whatever to accomplish what I want?

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CBA Member

delmarskid posted this 26 January 2022

They used to bend wood with hot vinegar or steam boxes.

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Brodie posted this 27 January 2022

I would steam it, but in truth, the grip will possibly cup again later. If it is not cupped too badly you can sand it flat on a board with sandpaper stretched across it. Also, if you are quick after you straighten the grips post steaming them you must saturate them with a finish that will seal the wood once it is dry they should not cup again.

B.E.Brickey

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TRKakaCatWhisperer posted this 27 January 2022

PEG (polyethylene glycol) is often used for permanent wood bending.

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CBA Member

GBertolet posted this 27 January 2022

How would you steam? Saturate the wood and place a hot iron against it, or hold over a tea kettle for a while. Maybe put in boiling water?

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CBA Regional Director

MarkinEllensburg posted this 27 January 2022

Build a steam box.

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CBA Member

Bud Hyett posted this 27 January 2022

Steaming the spot is only for dents. You have more than a dent as this encompasses the entire surface. This works well if done with patience and sealing with finish immediately after. My experience was with the commercial product Lin-Speed for sealant, I recommend it from experience.

Bent wood for baby cradles many years ago. The secrets are not in the bending, but the preparation and work afterwards. The sealing box was a cut up 35 gallon oil drum with two levels of grates. Fire underneath and water pan immediately below on the first grate, the wood on the second grate.

The wood was cleaned with alcohol after sawing and the rough edges planed to clean up.

Pull out when soaked. Then set on a pattern to repeat the same bend. Then set the pattern back in the steam to stress relieve for a few minutes (Always wondered if this really helped.). Pull out, let cool by air drying and apply sealant.

Overkill for your project, but I hope you understand the principles from the illustration.

Farm boy from Illinois, living in the magical Pacific Northwest

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CBA Member

delmarskid posted this 27 January 2022

You might try a double boiler for steaming. A metal basket over boiling water with cover?

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CBA Member

Eutectic posted this 27 January 2022

Pick a flat surface and cover it with a sheet of Saran Wrap or any kitchen wrap.

Put 1/2 inch of water in a deep pot and bring to a boil. You may want to soak the grip in water for 10 minutes if it is thick (over 1/4 inch), but this is usually not necessary. Hold the grip in tongs in the steam over the boiling water for 3-5 minutes. Put the grip flat side down on the plastic wrap and cover it with a towel. Put weights on the towel to hold the grip flat. This must be permeable so the grip can dry from the outside in. A 25 pound bag of shot works nicely. Allow the grip to dry, several days.

Sometimes there is spring back and you may need to put one or more thicknesses of 3x5 card on the outside edges. Don't get too much or you can get a reverse curl which is worse. A slight cup can be taken up by the grip screws.

I like boiled linseed oil to preserve the wood. I apply it to the dry wood and let it soak in. This takes several applications on new wood and rubbing with fine steel wool to remove hairs. This is another discussion and there are several products and finishing approaches.

Steve

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CBA Member

GBertolet posted this 27 January 2022

I got the situation resolved, but not the way I expected. A letter from the vendor (Numrich), if warped, said to heat the grip with a light bulb, and flatten it. Apparently the grip was not made of wood. I heated it over the wood stove, placed the grip between two pieces of wood and compressed it in a vice. It went flat, but after an hour in the vice, when released, it became cupped again, but not quite as much.

Out of frustration, I put a piece of sandpaper, on a flat surface, and sanded the grip. In no time the cup was gone. Apparently the cupping was not as bad, as I first visualized. Anyhow after that, I trued up the other grip also. Mission accomplished. I heard that some of these grips were made of animal horn. I think this might be one of them, by the way the sawdust looks.

Thanks guys for all the suggestions!