Removing seams off funnels?

[Gern]

With any seam, I always run some Extra Thin along it after it's started to set. The idea is to make sure that the joint is fully glued all along its length. If it isn't glued together you'll have a gap all the way through the thickness of the plastic which won't sand away.

[BattleshipBob]

Hi Bob. On a curved surface the best way to sand a seam is to sand wet at 45 degrees to that seam. That will minimise the possibility of thruppenny bitting the part, ending up with flat spots. It’s standard practice in model railway loco building to ensure the boiler remains round.
Your idea of marking the seam before work is a good one, but if there is an appreciable cavity in the seam I would fill it first.

Hi Tim, good advice, thank you!

With any seam, I always run some Extra Thin along it after it's started to set. The idea is to make sure that the joint is fully glued all along its length. If it isn't glued together you'll have a gap all the way through the thickness of the plastic which won't sand away.

Good idea, thanks very much!

[Tim Marlow]

Forgot to say, the sanding medium (wet or dry or what have you) should be fixed to a hard flat backing. This will ensure it takes off high spots but does not generate hollows.

[JR]

?:smiling3::thumb2:
Hammer , fire , or a liberal coating of 4BO.

[BattleshipBob]

Hopefully finished the funnels

You can still see the remains of the sprue attachments, never quite sure if these need to be totally removed?

[boatman]

YES Bob m8 sand them down
chris

[Tim Marlow]

Looks good Bob. I’d say the sprue scars only need to be removed if they show under the paint.

[BattleshipBob]

YES Bob m8 sand them down
chris

Cheers Chris, not long for f an s!!

Looks good Bob. I’d say the sprue scars only need to be removed if they show under the paint.

Thanks Tim, no ridge so will prime and fingers crossed!

[Jim R]

Hi Bob
Lots of interesting ideas and approaches to the issue. When a part is removed from the sprue, by whatever method you use, the plastic around the attachment point often gets stressed. You can sand back the attachment point nib left until it is perfectly smooth but the stressed area may still show. That is one reason why I use a primer coat - it show whether the area is ready for paint or needs further sanding or filling. As Tim says ....

I’d say the sprue scars only need to be removed if they show under the paint.

Jim

[wasdale32]

Hi Bob

The IPMS Seam scraper (#1) ( Products – Seam Tools – IPMS (UK) (ipmsuk.org) ) is a good investment for scraping seams on curved surfaces

[zuludog]

I don't make ships so I have never needed to sand a funnel.
But I do make planes, and sand things like bombs and rockets

Usually when you sand the joint or moulding marks of those you obtain a good circular cross section, which would be a circular or a sort of oval section for a funnel You might need a bit of filler or Mr Surfacer to fill any small gaps but it should still line up OK
However, sometimes the two halves of a bomb are offset so the only way to obtain a smooth joint line would be to sand off so much plastic that you end up with a flat surface instead of a continuation of the round one

In this case I would roughly sand the joint and any flash, then fill the line & gap with filler or a piece of stretched sprue & filler, which would require more sanding & shaping to restore the cross section of the funnel, bomb, or whatever
So if your funnel is bad, try that, and check with a coat of primer before while you still have decent access, before complete assembly

[BattleshipBob]

Hi Bob
Lots of interesting ideas and approaches to the issue. When a part is removed from the sprue, by whatever method you use, the plastic around the attachment point often gets stressed. You can sand back the attachment point nib left until it is perfectly smooth but the stressed area may still show. That is one reason why I use a primer coat - it show whether the area is ready for paint or needs further sanding or filling. As Tim says ....

Jim

Thanks Jim, will so soon after primer!

Hi Bob

The IPMS Seam scraper (#1) ( Products – Seam Tools – IPMS (UK) (ipmsuk.org) ) is a good investment for scraping seams on curved surfaces

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Thats interesting!

I don't make ships so I have never needed to sand a funnel.
But I do make planes, and sand things like bombs and rockets

Usually when you sand the joint or moulding marks of those you obtain a good circular cross section, which would be a circular or a sort of oval section for a funnel You might need a bit of filler or Mr Surfacer to fill any small gaps but it should still line up OK
However, sometimes the two halves of a bomb are offset so the only way to obtain a smooth joint line would be to sand off so much plastic that you end up with a flat surface instead of a continuation of the round one

In this case I would roughly sand the joint and any flash, then fill the line & gap with filler or a piece of stretched sprue & filler, which would require more sanding & shaping to restore the cross section of the funnel, bomb, or whatever
So if your funnel is bad, try that, and check with a coat of primer before while you still have decent access, before complete assembly

Many thanks for the advice, appreciated

Bob

[wasdale32]

Thanks Jim, will so soon after primer!

Thats interesting!

Many thanks for the advice, appreciated

Bob

It's great for restoring gun barrels too

[Airborne01]

Hi Bob
Lots of interesting ideas and approaches to the issue. When a part is removed from the sprue, by whatever method you use, the plastic around the attachment point often gets stressed. You can sand back the attachment point nib left until it is perfectly smooth but the stressed area may still show. That is one reason why I use a primer coat - it show whether the area is ready for paint or needs further sanding or filling. As Tim says ....

Jim

I concur Commander!!

[BattleshipBob]

It's great for restoring gun barrels too

Just ordered, £6 inc p an p, worth a try!

Will feedback when i get it, thanks again