kerfing MDF, how much material to leave?

[Redd]

hi all

I want to kerf some 18mm mdf. I had a go at it over the weekend, but I left to much material, i think i left maybe 4mm, and it didnt work right, kinda crumpled instead of a smooth bend as there was too much material left.

so can i ask real quick, how much material should i be leaving? I'm reckoning its going to be a similar amount regardless of the thickness used.

 

[katellwood]

The depth of kerf is subjective to the radius you wish to achieve and the number of kerfs cut i.e. the more kerfs cut the less like a thrupenee bit (fifty pence for the younger of us) the curve will appear







these curved risers were kerfed then an additional kerfed piece placed in the inner radius to strengthen the original kerf (veneered mdf I know but the principles the same)

finally the amount of bend can also be dictated by the width of the kerf i.e. cut on a circular saw (table or RAS) as opposed to cut by hand with depth stops clamped to the sides of a tenon saw)

Try some test cuts at differing depths and centres and see what bends you get

 

[Redd]

cheers for the detailed reply. That is some lovely work there. Its a fairely time consuming trial and error process! however your right, its the only way to go.