Sharpening blades of a Mitre Trimmer

[woodworkingMK]

Hello, I got one of those Mitre Trimmers second hand and the blades are in a very bad condition. They need re-sharpening.

I want to send them to a professional sharpening service. My question is:

Do they originally come with secondary bevel? It seems like yes, but my blades are in bad condition and cannot recognize clear enough. I need this information so I can be prepared when I will talk with the sharpener.

 

[marcros]

I believe that they need to be hollow ground. You could look at lion framing if you wanted a specialist sharpener.

 

[Logger]

It is right, they are hollow ground. In UK, wessex pictures and mainline mouldings definitely do it. I think lion do as well. Any picture framing supplier who sell morso guillotine will help you.

I use wessex pictures personally and pay about £12.

 

[custard]

Do they originally come with secondary bevel? It seems like yes, but my blades are in bad condition and cannot recognize clear enough.

Morso blades do not have a secondary bevel, I think that's true for most mitre guillotine blades.

https://www.lionpic.co.uk/p/7747/Morso- ... uble-Ended

 

[woodworkingMK]

Recommendations in UK are useless for me. I live in a small country where there are not so many professional sharpeners, maybe this the first small scale guillotine that entered the country.

Today I went to the guy who sharpens my saw blades and planer blades, and he said he can't do it, he recommend me to go and ask some printing company who sharpens their blaes.

I went to one printing company and they recommended me a guy who sharpens their blades. I will talk to him tomorrow, but I need to be prepared, because maybe he never saw such blades. Maybe he will know, I don't know.

Maybe I should go and ask some picture framing shops also...

Meanwhile, what it means "hollow grind", and what about the secondary bevel. I want to know few basic things, before I talk with the sharpener.

 

[RossJarvis]

Recommendations in UK are useless for me. I live in a small country where there are not so many professional sharpeners, maybe this the first small scale guillotine that entered the country.

Today I went to the guy who sharpens my saw blades and planer blades, and he said he can't do it, he recommend me to go and ask some printing company who sharpens their blaes.

I went to one printing company and they recommended me a guy who sharpens their blades. I will talk to him tomorrow, but I need to be prepared, because maybe he never saw such blades. Maybe he will know, I don't know.

Maybe I should go and ask some picture framing shops also...

Meanwhile, what it means "hollow grind", and what about the secondary bevel. I want to know few basic things, before I talk with the sharpener.

I know nothing about these blades, but "Hollow Ground" is where the edge which gets sharpened is "rounded in" by the grinding wheel, this leaves a concave "rounded in" edge. Apparently this is recommended by Morso, who make good quality mitre shears. You also want the edge which is ground, the "bevelled" one to be at a particular angle. The best I can see is about 30 degrees. (Additionally the cutting part of the hollow ground side is often ground "flat" across the hollow to the correct angle which may be what some call the secondary bevel). In words this sounds nonsense so here's a link to a an article with a picture which may help even if it's for chisels;

https://www.canadianwoodworking.com/tipstechniques/hollow-flat-grinding

Here is another link for wood cutting saws which may also help....or hinder;

http://www.raphaelstoday.com/Pages/RightToolsForTheJob.aspx

It's also possible that polishing the "flat" side of the blade may help get the best cutting edge. Note that the "hollow" shown in these articles is exaggerated and it is likely not that noticeable in practice.

Printers use "guillotines" to cut through deep stacks of paper, so I can see why your friend recommended this guy. However the angle that is used to cut paper may not be the same as that for wood.

 

[Glynne]

Do they originally come with secondary bevel? It seems like yes, but my blades are in bad condition and cannot recognize clear enough.

Morso blades do not have a secondary bevel, I think that's true for most mitre guillotine blades.

https://www.lionpic.co.uk/p/7747/Morso- ... uble-Ended

I have the Dakota mitre trimmer and unfortunately it does have a secondary bevel, about 3mm wide. So grinding down to leave only a primary bevel would involve removing an awful lot of metal.
I just about managed to sharpen them using some lapping film but I would have struggled if the secondary bevels had been in a porr condition.

 

[Keith 66]

We had a couple of old mitre trimmers at the school where i work they had a straight bevel & were ground on a surface grinder with angle fixture to hold them.

 

[woodworkingMK]

I gave the blades to the sharpener. He will grind them with just one main bevel and no hollow ground. I hope the trimmer will perform as it should.

 

[worn thumbs]

It should be fine;I changed the blades on a Morso guillotine a few years ago and the new ones had a single bevel.To be realistic,a sharp blade with sub-optimal geometry will still be an improvement over a blunt one.

 

[woodworkingMK]

The point is not to be improvement over blunt one, but to be top notch performance... we will see.