Leather burnisher, blueprints anyone?

[Mocivnik]

I need a motor operated burnisher, but now I have a "problem" with discovering the design.

 

I know I can draw and turn one by myself, but does anyone has any blueprints already? I need something for standard sizes, from 2mm up to 15mm (knife sheaths, mostly).

 

I'm talking something simmilar to this:

[JLSleather]

Blueprint only necessary if you are mass-producing something.  Stick a piece of wood in a drill chuck, and make some grooves with a gouge or file, sand it right in place.  Obviously, for mounting on a bench or pedestal grinder, you'll need an internal thread to suit the arbor.

[JKHelms]

I bought one of the replacement burnishers from Tandy for 30 something dollars and bored it out 8n the lathe and threaded the end to fit arbor on my HF buffer. Works like a charm. 

 

[JLSleather]

Just a thought out loud here .... you guys know that you can buy 1 1/4 - 1 3/8" diameter oak dowels for a few bucks, right?  Building materials stores (menards, lowes, etc) call them closet rods. 

Edited September 11, 2018 by JLSleather

[Mocivnik]

@JLSleather Totally agree on that. But the thing is, if I get any of blueprint of the existing one, it might have details, which I wouldn't be aware of while turning my own. That's the only point.

PS: Is there any required cutting speed for leather? (Calculated as circumference of the burnisher x turns per second?) Because I'm really struggling, what speed should I use. I can't find any numbers anywhere. But just "something" isn't something, I'd like to deal with. I might have too much or not enough and the edges won't be as they should.

@JKHelms: 30$ for a single piece of wood, turned on a CNC lathe is about 20 times too much. I'm just not paying that much for it (not because I couldn't afford that).

@JLSleather: Yeah, that's exactly what I got. I have 45mm (around 1 3/4 inches) of beech, lenght of about 40cm (about 15 inches). I'll just turn it out from this, but about 100mm (4 inches) long only.

[JLSleather]

Don't know the "cutting speed", but I've seen ppl on this forum going on about a 2" diameter burnisher running at 3600 rpm, which I have always thought was WAY too fast.

I get very nice edges running a stick less than 1"diameter (effective dia. down in the groove closer to 1/2" / 13mm) in a drill press at about 500 rpm.  Honestly, I think some people just like to have more tools, necessary or not.

If you understand "cutting speed", you likely don't have any trouble making your own "blueprint".

Edited September 11, 2018 by JLSleather

[Mocivnik]

@JLSleather: calculated for you, it's about 333mm/s cutting speed, which is around 33cm or 13inches.

 

More tools than need? Who do you mean this goes to?

For me, I want to have all the tools, I need most often and some, which I use seldomly. For example, I want to have better (more expensive) tools for rivets, which are most common in my workshop, but I don't care if I have chinese tools for rivets, which I use seldomly.

[Mocivnik]

@JLSleather: Hah I did drawing in autocad of my own before I started this topic and here it is.

 

 

[RockyAussie]

Just wondering as I do at times ....if the convex bullet shape end would be better off concave to get inside those little tight areas? Nice looking picture there anyway.

[JLSleather]

AutoCad? So that would be a revolved surface then?

[Mocivnik]

@RockyAussie: umm..with the spike, you can get pretty close aswell...but the "cutting" speed is higher here aswell.

 

@JLSleather: Jup.

[Matt S]

I use a standard 2950RPM bench grinder motor on my Nigel Armitage/Just wood burnisher. Working diameter is about 2"/50mm. Yeah it's fast, maybe just on the high end of acceptable", but it works just fine and the price was right.

[koreric75]

21 hours ago, JLSleather said:

Blueprint only necessary if you are mass-producing something.  Stick a piece of wood in a drill chuck, and make some grooves with a gouge or file, sand it right in place.  Obviously, for mounting on a bench or pedestal grinder, you'll need an internal thread to suit the arbor.

did similar, i used my dremel and the "screw on" post for buffing pads to turn the little wooden knobs that are flat with raised edges, it takes a few seconds to swap one out for another and i can control the speed to suit the material.  I have a drill press,  and a 24" section of oak dowel "closet rod" just haven't chopped and put a gouge to it yet...the dremel takes up way less space, but i have to hold the material and the dremel .  I had an idea  awhile ago to use a variable speed router mounted in a benchtop router table with a turned groove to do belts and sand edges...you could adjust the fence and the height with the table and router adjustments, just haven't tried it out yet.

[bullmoosepaddles]

@JKHelms I hope you don't mind. What is the left disk on your grinder? It appears too be leather, if my eyes are not lying to me. Makes me curious.

Thank you

Gene  

[Mocivnik]

 

2 hours ago, Matt S said:

I use a standard 2950RPM bench grinder motor on my Nigel Armitage/Just wood burnisher. Working diameter is about 2"/50mm. Yeah it's fast, maybe just on the high end of acceptable", but it works just fine and the price was right.

Yeah, same here. All I can get, has 2950 RPMs, but I will regulate it with a dimmer (as I regulate all my resistive and inductive burdens).

I can get a benh grinder of 350W for around 45€ (40GBP or 50 usd), which I think it's reasonable price.

2 hours ago, koreric75 said:

did similar, i used my dremel and the "screw on" post for buffing pads to turn the little wooden knobs that are flat with raised edges, it takes a few seconds to swap one out for another and i can control the speed to suit the material.  I have a drill press,  and a 24" section of oak dowel "closet rod" just haven't chopped and put a gouge to it yet...the dremel takes up way less space, but i have to hold the material and the dremel .  I had an idea  awhile ago to use a variable speed router mounted in a benchtop router table with a turned groove to do belts and sand edges...you could adjust the fence and the height with the table and router adjustments, just haven't tried it out yet.

So did I, but I really dislike the dremel to use for this. I don't find it steady enough in my hand, so I'm into something more rigid.

[Matt S]

2 hours ago, Mocivnik said:

Yeah, same here. All I can get, has 2950 RPMs, but I will regulate it with a dimmer (as I regulate all my resistive and inductive burdens).

I can get a benh grinder of 350W for around 45€ (40GBP or 50 usd), which I think it's reasonable price.

So did I, but I really dislike the dremel to use for this. I don't find it steady enough in my hand, so I'm into something more rigid.

What dimmer do you use for an inductive load? My bench grinder has a brushless/induction motor, which I have read is very difficult to control the speed without powering it through a variable-frequency drive.

I have bought and built inexpensive Dremel burnishers. I don't like them because it doesn't take much of an imbalance in the wheel to cause a lot of vibration. With a bench-mounted burnisher a small amount of imbalance is counteracted by the mass of the bench it's bolted to. Further, with the cheap Dremel clones I have the speed is way too fast, and because of the simple circuitry you lose all power when turning the speed down.

[Mocivnik]

Actually, a very regular dimmer. 

The one which is for the light, but you have to be careful, that in the datasheet (or just on the packaging) it shows that its availible for R, L and RL loads. 

But sometimes, you have to change the original triac for a better one, as the m9tor at the start can draw up to10 times or more current than regulary does. 

I use the dimmera for ~5€ and switch a triac for another 1€ and e-voila

Oh, and not to forget to mention, with dimmer, its not very accurate regulation, but its a cheap one. frequency regulators cost couple of hundreds of € each and its an overkill for this application. 

And yes, I agree 100% with dremel-bench grinder point of view. 

Edited September 12, 2018 by Mocivnik

[JKHelms]

5 hours ago, bullmoosepaddles said:

@JKHelms I hope you don't mind. What is the left disk on your grinder? It appears too be leather, if my eyes are not lying to me. Makes me curious.

Thank you

Gene  

It’s a series of scrap leather discs I cut and glued together to use for stropping my cutting tools.  

Works pretty good.

[Matt S]

24 minutes ago, Mocivnik said:

Actually, a very regular dimmer. 

The one which is for the light, but you have to be careful, that in the datasheet (or just on the packaging) it shows that its availible for R, L and RL loads. 

But sometimes, you have to change the original triac for a better one, as the m9tor at the start can draw up to10 times or more current than regulary does. 

I use the dimmera for ~5€ and switch a triac for another 1€ and e-voila

Oh, and not to forget to mention, with dimmer, its not very accurate regulation, but its a cheap one. frequency regulators cost couple of hundreds of € each and its an overkill for this application. 

Interesting, I'll try a lamp dimmer. I'll look for one rated for inductive loads. I have a motor that I don't mind risking for the sake of an experiment.

I agree, a VFD is overkill for a burnishing machine but it's what an electronics engineer advised me was the only electrical option for slowing an induction motor (other than modifying the coils or adding a physical brake!).

[gigi]

I've also made a sketch for a burnisher a while ago, with different type of grooves, bought the wood but never completed this project so I don't know how good it works : 

[Mocivnik]

@matt s: Yeah. 

The motor will not be hurt anyhow. What the dimmer actually does, is this:

 

The original voltage input is pure sine wave, but the dimmer is just chopping it at the end of it and the "average" voltage is lower. It's also the negative feedback to the electrical network.

 

 

But, whoever you have been talking to, they didn't tell you about a better solution either, a variac. This is nothing but an adjustable transformer. Which means, you can regulate voltage linear, but the outcome on the motor RPMs might not be (100% will NOT be) proportional. But, it works perfectly, it's not a bad feedback to network, but it's not linear (seen from motor side). But it's usable. The price? Used you can get for 50-100$. Just buy it same (or a bit more for sure) like 500W or 1kW variac on ebay and you're good to go. It's like a potentiometer, nearly without loss (98% efficiency). I'm buying mine this month (for electrical stuff I need, as I'm electrical engineer by education).

https://en.wikipedia.org/wiki/Autotransformer

[RockyAussie]

12 hours ago, Mocivnik said:

@RockyAussie: umm..with the spike, you can get pretty close aswell...but the "cutting" speed is higher here aswell.

 

@JLSleather: Jup.

I guess if you have a variable speed motor that would not be an issue. I don't do much with burnishing but I would think about using a brushless   servo motor as is now commonly used in the sewing machines. I bought a 550 watt one with all of the stuff associated to mount to a sewing machine here for $119AU (about $80.00USD). With that I can set the fast speed where I want and climb up to that steadily if I use a foot control as well. Could also just mount a turn down knob on a spring to vary the speed on the bench. I do think having a spike that can get inside small areas like crew punch holes would be an advantage especially those big holster ones I see at times. I notice a lot have trouble getting them to look well finished if they do it by hand.

[bullmoosepaddles]

8 hours ago, JKHelms said:

It’s a series of scrap leather discs I cut and glued together to use for stropping my cutting tools.  

Works pretty good.

Thank you Sir. Now I feel silly. I have a much smaller one made by Flexcut that goes into my drill press. The vertical appearance threw me.  

[Mocivnik]

Finally done. I've actually finish it last weekend, but I didn't took any photos (although I thought I did!) so I was able to take new photos only now.

Made from beech, diameter is 40mm, lenght ..I don't really know :D Grooves are from 16mm down to 3mm.

Burnishing machine is a "cheap" chinese one, got new for 45€ (52$).

350W, 2950 RPM, I think it's working great. I didn't had much of a chance to test it out, but plan to do it at end of October (when I'll be back from travelling UK).

 

 

Edited September 23, 2018 by Mocivnik

[dikman]

I'm still not convinced that a light dimmer can be used to vary the speed of a squirrel cage AC motor.