Any advice on how to cut/file a 45 degree chamfer on a 1mm steel sheet to EXACTLY 45 degrees?

I will second that, simple to make and set-up and will also give repeatable accuracy.

Emgee

I've seen 3 chamfering devices recently on Instagram and Youtube by Oxtools, Robin Renzetti and Stefan Gotteswinter. They are all based on the same basic idea, a V block with a milling cutter projecting into the bottom of the V. All handheld, all look capable of consistent, accurate results.

Oxtools , Renzetti, Gotteswinter 1,

Also a different approach:

Gotteswinter 2

W.

Not sure how well any of those would work on the OP's "knifeedge" and they are also small parts which will take your fingers close to the cutter, may be OK for knocking off corners on larger items where the "V" supports two edges of the work.

Another thing to consider is that running abrasive grinding points along lengths of 1mm thick steel is going to wear grooves in them very quickly.

I've got to cut some dado rail to 'exactly' 45 degrees in the next few days.

Far trickier if you ask me...

Neil

I would make a jig (wooden perhaps) and use a bench grinder.

Perhaps grind chamfered end first, then grind other end to exact length.

You've got your priorities wrong Neil, should be workshop first then DIY.

J

PS Painter's mate is your friend

PPS Luck your house has all the walls at Exactly 90deg

Internal or external corner.
For the internal, cut one piece to 45°; saw along the witness line of the profile to 90° with a fine coping saw.
Works well for full depth complicated skirting boards too.

Butt joint to a plain length already fitted into the corner.

Bill

"PPS Luck your house has all the walls at Exactly 90deg"

As if that has ever happened! (I'd settle for 'somewhat planar' in our house)

In the spirit of the OP's expectations of 'EXACTLY' I would say that most houses are walls at exactly 90 degrees.

In our home I could put a square table in the corner of a room and it might fit perfectly but I dont know for certain that the table is accurately made.

Personally I dont have a high opinion of British housebuilders but I accept fitness for purpose serves here.

Ian P

That's what mitre boxes are for. You can buy plastic ones for a few quid these days. Guides the saw at exactly 45 deg and perfecty square. (By woodworkers standards, which if my mate the builder is anything to go by, are not quite up to Michael Gilligan's typical parameters.)

Which maybe could be used for the OP's problem too. Glue some emery paper to the side of the saw blade and hold the job in position on the side of the mitre box while chamfering the edge.

I'm not sure what 'magnetic guides' are but if you want the magnetic force to hold these parts together at right angles and you are concerned about a 0.1mm potential gap you might need to use guage plate or have the steel parts hardened.

Since these items have more or less a cutting edge (like a plane blade) they will be very subseptible to damage or burrs so even if it was a perfect 45 degree bevel it might not remain so for very long.

Since you mentioned this was an idea for a 'product' it might be sensible to have a batch made by an engineering company or an individual rather than buying machinery and learning how to use it. As others have said the most appropriate DIY method is that suggested earlier by Andy Stopford .

Are you hoping that the magnetic force will hold two parts together at a right angle just by the contact along the bevelled edge?

Ian P

Scribe internal corners on any mouldings and mitre external, As Peak4 said precutting a "mitre" and then using the edge as your scribing line is the way to do it.

Dare not tell Neil that Dado rails is about as popular as the similar named bird these days can't remember that last time I fitted any for a client even in period properties.