Kerf allowance in a commercial cabinetmaker shop?

Hi Folks,

I am thinking about getting some speakers made, and to make things a little easier I was planning on asking a commercial joinery firm to cut the panels from the sheet goods. I will just do the speaker holes, internal baffles etc and assembly.

To help get an idea of cost I was experimenting with a few different cut list / panel layouts.

Just a couple of questions if I may:

1. In a commercial shop, what would typically be the kerf allowance when spacing the panels on the sheet?

2. If I needed a 45° bevel along each edge, would they cut the bevel straight from the sheet, or would they break the sheet down using 90° cuts and then come back and cut the 45°?

3. In the scenario above, if they do the 45° after breaking down the sheet first - does this increase the kerf allowance during the breakdown, or do they cut square to exact panel size and then create the bevel?

Cheers

Stinky

Stinky, I suspect that you are overthinking this. :)

If I wanted a specific size with a bevel edge, I would size it to finish at that specific size.

You specify the size you want it to finish at. Let them do it the way that they prefer.

Regards from Perth

Derek

I am prone to overthinking Derek!

I agree that they will do what they want, however I’m trying to work out if I can get all of my panels from one sheet, or if it will push it over to two.

There is a considerable cost increase going from one sheet to two sheets - including considerable wastage. Based off my rough guide if I increase from a 1200 x 2400 sheet to a 1200 x 3000 it can all fit on one sheet - this is based off just under 5mm per kerf cut.

And yes .... I have found somebody who has veneered mdf in 1200 x 3000 :)

I think it was Elan who put me onto a free program called MaxCut V2.
Great program to work out the best way to cut from a sheet. Allows you to enter the kerf etc.

Are you designing your own crossover for your cabinet or are you going to use a off the shelf crossover?

Thanks Lappa ..... I have used layout software in the past for complex jobs and it’s a good tool - but you still have to enter in the preferred kerf allowance which I don’t have. This is a relatively simple layout so I just do it in CAD. As I need to consider grain orientation of the timber veneer options of panel layout are reduced further.

The crossovers will already be designed and built. I’m just doing the enclosure construction to save a few dollars and I think it would be fun to do. I am purchasing through a small local speaker manufacturer who typically sells complete speakers, but offers kits as an option.

Standard saw blade is 3.2mm, if it's being nested on a CNC router, probably allow 12mm kerf for a 10mm bit.

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Originally Posted by elanjacobs

Standard saw blade is 3.2mm, if it's being nested on a CNC router, probably allow 12mm kerf for a 10mm bit.

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Thanks - exactly what I was looking for. I try to allow 5mm for a standard kerf when doing a rough idea of setout. Having not seen too much CNC work 12mm is a surprise, but makes sense to have a larger bit for the thicker material.

Fortunately I just found out the panels were 20mm shorter than I was expecting, so that has given enough cover both standard kerf or CNC.

Just out of interest if a job landed in your workshop requiring 45° bevels, would you rip the sheet with the blade angled for the bevel, or 90° cut the panels and then cut the bevel? (bevels all going the same direction so no need to flip board to have the short edge on the veneer face)

Yeh, 12mm seems like a lot but at the speed these routers move (12-20 m/min) you need a decent size bit or it will just snap; generally you'd run a 10mm bit up to 19mm material and a 12mm bit up to 32mm material. The waste in material is easily offset by the efficiency savings

We'd always cut square, leave 1mm per beveled edge and do that afterwards. Full length rips on a 45 are a nightmare for a few reasons: a) if the panel droops as it comes off the back of the table it will rub on the blade and stuff the cut, b) mitred edges are super fragile, so you want to keep them square as long as possible, and c) they're bloody sharp, so the smaller the panel is when you have to handle it, the better.

Quote:

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Originally Posted by Sir Stinkalot

There is a considerable cost increase going from one sheet to two sheets - including considerable wastage. Based off my rough guide if I increase from a 1200 x 2400 sheet to a 1200 x 3000 it can all fit on one sheet - this is based off just under 5mm per kerf cut.

And yes .... I have found somebody who has veneered mdf in 1200 x 3000 :)

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Just a small caution ...

are you absolutely sure that the 1200 x 3000 sheet is actually those dimensions?

Last time I was shopping in AUS the sheet size was 1220 x 3050 (i.e. 4 ft x 10 ft)

Ply tends to be metric, everything else is usually imperial, BUT veneered panels seem to be somewhere between the two; they press onto imperial board, but a bit gets lost when they trim the panels after

Dont forget to allow for a trim cut on one end and one side to square up and clean the starting edge.