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

Hello

I need to make about 32 identical, small pieces of rectangular mild steel plate with dimensions: c.16 x 13 x 1mm.

The tricky bit is that I need to put a chamfer on one edge of the steel that is EXACTLY 45°.

Background
It is just for a novel product idea that I am working on.

I am thinking that in principle I just just cut a long strip of steel that is 13.1mm wide, and put a 45° chamfer on it and then cut it up into 16mm lengths.
My first problem would be cutting a long strip of steel by hand (using a hacksaw) reasonably accurately, before I file it flat.

But even more difficult would be putting an ACCURATE 45° chamfer onto one edge. With enough time and very careful filing and sanding I suppose this is would be possible, but not easy!

So was thinking that maybe I should buy a small desktop milling machine.
Any suggestions?

With thanks

J


PS FWIW, I do own a small Proxxon drill, with a small Proxxon Micromot 50/E rotary drill with possibly I could use a small grinding wheel. However although it seems very well made, and spins at up to 20,000 RPM, it's only 40watts. And in any case I fear that there might a bit of chatter, no?

So do you think I should add to what I have got...?

e.g. Possibly I could add a Proxxon "MICRO compound table KT 70"
https://www.proxxon.com/en/micromot/27100.php

Possibly with some sort of vice(??)


However according to this youtube video this table suffers quite badly from wobble !
https://www.youtube.com/watch?v=Ws6UwE1qB2I

OR should I just start again from scratch and buy a different system?

NOTE: I have never used a milling machine before, so although I am keen to buy something that is well made with good quality, I am needing to be cautious. Also I just have a very small home workshop so whatever I buy needs to be pretty compact!

Any advice?

J

You could use a 90 deg spot drill but I don't think you will have much success with the tools you have, a small milling machine would cope with such work.
It would be usual to fix the material to be cut and pass the tool across but you may be able to make up a jig of some kind to hold the plate and push the job past the fixed cutter.

Emgee

I don't know how well it'd work in practice but with only access to rudimentary equipment I'd be inclined to bond the strip of steel between 2 lengths of MDF, say 9mm and make up a jig and fence and run a conventional router with a 90 deg cutter along it. A TCT router cutter should cope with 1mm steel OK in such a sandwich.

pgk

If you truly need an exact 45 degree angle as you say, I suggest a sine bar setup to make an accurate jig to hold the work in a surface grinder. You will get an exact 45 degree angle very accurately positioned from an edge with this method.

Faffling around with plastic toy tools as you show in the pics is much less likely to produce accurate results repeatably.

Put a grinding wheel in the proxxon drill. Set the (a) fence at 90 degrees to where you have it now and the correct distance from the wheel.

With the grinding wheel flat you could do the back edge, Tilt the wheel to 45 degrees reset the distance to the fence and grind the chamfer. You should have enough power for 1mm steel sheet.

Edited By Peter Cook 6 on 22/03/2021 23:36:14

Emgee - Can you recommend a good quality, compact milling machine?
My small home workshop is extremely small and needs to be tidied away most nights.
What would be the things to look out for?

Peter Cook 6 - I quite like your thinking but
1) My Proxxon Micromot drill can handle up to 3.2mm shafts. The problem is that I can't find a decent grinding wheel that will fit it!

2) I can't quite work out how to attach the guiding blocks that you have drawn onto the base of the stand.
Do you think that I should:
a) Buy a special a table for my Proxxon stand + drill? OR
b) Cut my losses and buy something completely different.?

Frankly it all looks a bit pathetic/toy-like!

To get clear, although it's broadly a good thing for my machinery to be pretty small, so long as they are well made... Either way I need precision!

BUT like I say, I really don't have much physical space for all this...

J
 

PS I feel in my bones that I should be using something much more powerful. e.g. I have this (slightly beaten up) 750watt hand drill.  (See https://www.amazon.co.uk/Bosch-PSB-750-Hammer-Drill/dp/B003UES78K)
Maybe I could buy a stand for it?

OR

How about buying an actual milling machine - albeit a compact one...

e.g. "Proxxon Micromot MF 70Milling Machine"
https://www.amazon.co.uk/Proxxon-Micromot-MF-70Milling-Machine/dp/B002H5AH5O

The trouble is that again it just looks rather under-powered. Only has 100 watts. Weights 7Kg (almost too little, no?)

J

Edited By John Smith 47 on 23/03/2021 13:11:37

Come on Jeff, get real He has very little kit and no room for even a small mill let alone a surface grinder He is asking for advice. Not a scathing unhelpful comment from someone who obviously has a lot of kit

Given the tools to hand I think I would cut the rectangles first, a bit oversize on the 13.1mm dimension then drill the Holes.

Make a simple jig with two tapped holes so the work can be screwed to it. Then set jig at 45deg and use a cut off disc in the still vertical tool to cut the edge to 45deg, less chance of wear giving differing sizes or clogging which you may get with a grinding bit.

Edited By JasonB on 23/03/2021 13:08:49

If you want to set an exacyt angle then a sine bar as has been suggested is the way to go to mount the work.

If however you are looking to make a mitre that will join to make a 90 degree corner then I suggest you mount the two pieces square to each other and run a cutter between them to acieve two exactly matching bevels. If one is off by half a degree the other will compensate by being off in the other direction. It always helps if you give some details of what you are trying to make.

regards Martin

You say sheet steel but you may be better with gauge plate, it will be flatter to start with and cut better than soft sheet steel. I would clamp the piece standing up, rough cut with a small carbide cutter, Dremel type not mill type, then finish to size with diamond cutter. You could try any combination of cutter materials, just bear in mind the speeds your spindle is capable of.

The real question is how accurate does "exact" imply? Until that is quantified then what kit one may, or may not, have is irrelevant.

Andrew

Thanks for all your quick responses
[Note I have now added a PS to my post of 12:36 today]

Regarding accuracy of the 45 chamfer, I need to make a bit load of them at least 32 of them and they ALL need to be able to meet and create a 90° join.

The reason for the accuracy is thatt they are for magnetic guides and even a 0.1mm gap will cause a significant drop in magnetic pull.

I was planning to cut a long thin bar of c13.5mm wide out of a 1mm thick sheet, put a chamfer on it (or the other way around??), and then chop it up into 16mm lengths and then drill holes the holes them.

I have yet to work out a good way to cut the plate accurately. I have a hand held Nibbler like this:

But even when used carefully makes a bit of mess of the steel sheet!

Obviously I don't have a band saw in my tiny/portable workshop. Spining cutting disks seem to make a bit of a mess of long cuts. So for now I am stuck with either a hacksaw or one of these Jeweller's 4" saw frames:


https://www.cooksongold.com/Jewellery-Tools/Adjustable-Saw-Frame-4-Deep-prcode-999-736



But we digress!

Back to my chamfer. I'm not sure how a Sine Bar would really help, except to mark things up - but I have various triangular measuring squares that can give me an accurate 45 degrees.

HowardT - what exactly do you mean by a carbide cutter and a diamond cutter?

Do you mean high speed spinning disks?

If so, my problem is that when cutting by hand, I find it impossible to cut longer cuts very accurately using a disk. I think I need some kind of milling table.

Fwiw I have also tried cutting wheels wheel (e.g. HSS) but the seem to go blunt in a blink when cutting steel. [Maybe they can't cope with 20,000 rpm?]

Also why are you using a diamond cutter as well as a carbide cutter?

Edited By John Smith 47 on 23/03/2021 13:50:39

In magnetic terms 0.1mm is a pretty big gap. With the existing design and kit available I think you'll be wasting your time. Far better to invest that time in coming up with a better design. Why can't the part be bent from a single blank? Even if the angles could be made accurately how are you going to hold the parts together? Ferrite cores, gapped or otherwise, come with stiff springs to hold them together for a good reason.

Andrew

Andrew - Sorry, no I am not in a position to seek public opinions about our design. So no, I am not in a position to disclose the details of the design.

Sufficeit to say that no, the part absolutely CANNOT be bent from a single part.

It would help me if people focus on the specific issues and actual questions that I have raised, rather than going off in tangents. We emphatically don't need perfection, we just need it to be as accurate as we can get it within reason.

Edited By John Smith 47 on 23/03/2021 15:01:56

Hi JS 47,

I appreciate your dilemma with a small workshop space. A little more detail of what you are trying to achieve might render some more suggestions.

I was referring to the material of the cutter that is doing the cutting. If you look at cutters on the Dremel site you will see cutters with the letters HSS, which stands for high speed steel, and others may say carbide and again diamond. HSS and carbide cutters are usually solid metal, carbide is a sintered powder usually harder than HSS when formed. Some cutters are diamond coated which is used for lighter cuts in hard materials.

If you are cutting sheet steel then HSS might be adequate at least for trials when roughing then use a diamond wheel to finish to get the accuracy you want. Holding the piece perfectly parallel to the cutter is the key to achieve what you want so a little fixture with pins and clamp would do and slide it along a guide under the fixed cutter.

JS47, file one edge of the sheet straight. Then use a hacksaw to cut off a strip say 14mm wide does not have to be 100% straight. Then hacksaw into pieces and file the two ends to give lengths of 16mm and drill. You can now cut the 45edge as I suggested which will clean up the wavey sawn edge and leave it at 45deg.

I would use the same method if doing it with a mill, except the 3 other edges would also be milled at 90deg to the face and at right angles to each other and obviously use a milling cutter rather than be limited by what you can run.

Edited By JasonB on 23/03/2021 15:51:36

How about a different approach?

First, cut your steel into pieces of the size required but leaving say 5mm on the edge where the 45 degrees is required. Find yourself a slab of steel with a good flat face, big enough to accommodate the full length of the 45 edge, and ensure that is is properly flat - perhaps get a local engineering firm to do this bit. While you are there, ask them if they could prepare a bar of tool steel with 5 faces - like a long shed with flat floor and walls, and a roof at 45 degrees each side. This should be hardened and tempered. The cost of doing this will be way less than buying new machinery.

Then you need a big solid vice, or a bottle jack, and add some ingenuity, so you have some way of forcing the roof of the 5-sided bar into the steel plates at exactly the right position, one at a time, until the edge is cut away. This will mark the slab each time, so move across the surface with each piece to avoid marking the back of the workpiece.

This should give you edges which are as accurately 45 degrees as the tooling itself. Wrap some fine wet-&-dry paper round a flat file and run this along the finished edges to remove any burrs. The sharper the roof edge and the flatter the slab, the more tidy will be the product.

Hope this helps

Cheers, Tim

I would suggest hacksaw/bandsaw sheet metal blanks & then finish mill all round to get all 32 parts any where near 'identical'. Warco, Chester or Arc Eurotrade sell suitable mills. Trying to do this job by hand is not really an option.

Tony