Dust collection fittings advice

[nosuchhounds]

I need to set up a slightly more permanent dust collection set up but im a bit baffled by dust port sizes. Are the dust ports on machines measured by the internal or external dimensions? I have a RP DX1000 which has a 100mm hose but all my machines (trend Crt router table, Triton Thicknesser and Axminster Trade bandsaw) all have different sized dust ports it would seem. Will this compromise any flow?

Apologies for what might seem like obvious questions

 

[ChaiLatte]

Are the dust ports on machines measured by the internal or external dimensions?

Yes. No. Maybe. Both.

All answers above are likely to be correct as there is no consistency.

Will this compromise any flow?

If something gets bigger in the direction of flow, it will not hurt. If something gets smaller in the direction of flow, it would be best to do so by a long, slow taper rather than an abrupt step.

In the 100mm 'area', there is cooker hood ducting and soil pipe; combinations of both might assist. Being thermoplastics, a heat gun can also make things fit by stretching (shrinking is harder and might need a mandrel).

You can cut out a small section of a larger pipe and butt the two ends together to reduce diameter to make an internal fitting as the elasticity of the pipe will keep it in place. Make it slightly oversize and tune up with a file.

If you have Ninja skills and want an external fitting, you can make the joint like a jigsaw puzzle or dovetail (or solvent weld two pieces together - imagine an O surrounded by a C).

3D printing allows you to go from any size to any size.