Laser cut kit tolerance issues

[Dan JordanParticipant @danjordan90150]

[Dan JordanParticipant @danjordan90150]

Decided to return to the world of modelling after some years being dormant.

Treated myself to a Graupner Sophia model boat. It is an all wood scratch build kit.

The parts are all laser cut but I think there is an issue with the laser cut tolerances. The hull spars and cross bearers have notches cut in them where they are supposed to slot together. I appreciate these should be snug, but not one I have tried to assemble, fit. I am having to carefully file each cut out, on every joint that I wish to assemble. Surely this can’t be right? There are dozens and dozens of joints to file out.

Can anyone confirm is this is normal or is there a tolerance issue with my kit?

[Dave MilbournParticipant @davemilbourn48782]

Dan

I can't comment on your particular kit but when I specified a slot which was routed at exactly 3.2mm wide from SLEC then that's what I got. You could almost hear the air hissing out of the join when I fitted the corresponding 3.2mm ply piece.

As I understand it, the program to convert CAD files into router or laser cutting files involves specifying whether you want the cut centred on the drawn line or to one side or the other. Maybe 'Graupner' got it wrong?

Sorry I can't be of any more practical help but it seems that you're stuck with what you have.

Dave M

[Colin BishopModerator @colinbishop34627]

I can confirm what Dave says. I have been building two of the Fairey kits designed by him and all the pieces, whether liteply, birchply or clear plastic fit exactly. The main framework of the boats is such an exact fit that they hardly need gluing.

Colin

[redpmgParticipant @redpmg]

Hi Dan – can tell you from experience with our commercial laser production that sometimes there is an issue with slots. Not all plywood, MDF , HDF or even perspex are always the quoted size. Recently on an order for perspex trophies found 3 items out of 14 after cutting were 6.5 mm wide not 6mm as sold although the rest from the same sheet fitted – some slightly loosely, This meant we had to enlarge the slots in the base for the oversize ones – similarly 3mm wood of all types can vary from 2.7 to 3.6mm which means since the slots are cut to 3mm that some are a sloppy fit and some do not fit at all. This applies to thicker sheets too, Dowels we use for axles are also a problem – 6mm ones can vary from 5.6 to 6.6mm.- so we have to measure those at the shop before purchasing……….

It would seem in your case Graupner have either been supplied with over thickness ply or they used the wrong size

[Dan JordanParticipant @danjordan90150]

Thank you for your replies guys.

Do you think I should speak to the model shop and try to return the kit?

I have pressed out most of the wood parts. I haven’t glued anything together yet. I have fettled some of the hull to get them to fit together though.

[Dave MilbournParticipant @davemilbourn48782]

Dan

If you've started building the kit to any degree then I suspect you'll not get very far in trying to return it to the shop and obtain a refund. There may be some recourse to the manufacturer if the parts supplied are measurably different from their description e.g. something described as 3mm ply is actually 3.2mm thick. However I believe that Graupner kits are made in ROC these days. In my experience Chinese suppliers are rarely tempted into correspondence with end-users!

Another remedy might be to sand the parts down a little in thickness so that they fit into the slots.

Dave M

[Colin BishopModerator @colinbishop34627]

Dan,

I'm afraid that it not uncommon to encounter this with kits for the reasons suggested by Redpmg above. Both quality of design and materials can vary, wooden boat kits don't commonly don't click together like injection moulded plastic kits.

I suspect the manufacturer may play it safe by making the slots a bit small as it is a lot easier to simply open them out compared with rectifying a loose fit with gaps. Usually this simply means more fettling as part of the construction process which is all part of the fun! I would be inclined to bite the bullet and persevere, you will find it takes less time that you think when you get going. Looking at the online construction photos:

**LINK**

I don't see a huge amount of work involved and the finished product looks very attractive.

As well as filing, a sharp craft knife carefully applied can shave off unwanted material quite rapidly.

I have noticed with the SLEC Fairey kits that the quality of wood is superior to the offerings of other mainstream manufacturers that I have seen – but then they are a specialist wood supplier.

Colin

[Empire ParkstoneParticipant @empireparkstone]

I have noticed with the SLEC Fairey kits that the quality of wood is superior to the offerings of other mainstream manufacturers that I have seen – but then they are a specialist wood supplier

Not to mention an advertiser here

r

[Ray Wood 3Participant @raywood3]

Yes,SLEC are excellent and the majority of my wood both Balsa & ply are purchased from them either at the summer shows or mail order 😀

Regards Ray

[Dan JordanParticipant @danjordan90150]

Thank you all for your help and advice.

I will keep the kit and spend more time making everything fit snug. I guess I was being a little impatient regarding the build process.

looking forward to getting it finished !

[Chris FellowsParticipant @chrisfellows72943]

You did say it was a scratch build kit!

Chris

[Empire ParkstoneParticipant @empireparkstone]

Posted by Ray Wood 2 on 27/10/2019 15:25:01:

Yes,SLEC are excellent and the majority of my wood both Balsa & ply are purchased from them either at the summer shows or mail order 😀

Regards Ray

Wow you also getting discount

[Colin BishopModerator @colinbishop34627]

Empire P, none of us are employees of either MTM or SLEC, we are just giving our considered opinions as modellers so your remarks are uncalled for.

I have a partially made kit by a major manufacturer which I have given up on as the quality of wood was poor, and they are not the only culprits.

Good service and quality should be highlighted wouldn't you think?

Colin

[Empire ParkstoneParticipant @empireparkstone]

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