Author Topic: Minnie on the cheap!  (Read 1943 times)

Offline chipenter

  • Hero Member
  • *****
  • Posts: 726
  • Country: gb
Re: Minnie on the cheap!
« Reply #25 on: October 04, 2017, 11:59:11 AM »
I make my own gear cutters as horological cutters are £80 plus each , Doc did a video on making single point cutters slower but gentle on the machine .
Jeff

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #26 on: October 04, 2017, 12:04:24 PM »
It's reassuring to know that people are watching.
Now, to go back to my question. If I use single tooth cutters I will need to buy several to cover the range of sizes. If I use a hob, one size will cut all of the range of gears required. But, the hob is cutting more than one tooth at a time. Will the half HP motor on my mill have enough power to drive a hob?
Yes, I have considered making the cutter, in fact I would prefer to, but the cost of the materials makes it hardly worthwhile. One mistake, and I do make them, would make it cheaper to buy the ready made cutter in the first place.

Offline chipenter

  • Hero Member
  • *****
  • Posts: 726
  • Country: gb
Re: Minnie on the cheap!
« Reply #27 on: October 04, 2017, 12:07:45 PM »
One point cutters are made from silver steel and hardened , cheep as chips just run slower .
Jeff

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #28 on: October 04, 2017, 12:30:21 PM »
25mm silver steel is £18 for 300mm, I don't think that is cheap. Plus I would have to buy silver steel and other steel to make the cutters to make the cutters.

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #29 on: October 04, 2017, 12:32:55 PM »
I have made the blanks for all of the gears except the largest, I don't have any material for that. I have made them in brass as that is what I have.

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #30 on: October 04, 2017, 12:37:32 PM »
I have also completed the smokebox and the perch bracket.
I bent the tube for the smokebox from 1.5mm sheet and welded the joint. That was a test for my welding, I initially burnt a hole in it but with a bit of practice I was able to weld a patch in it. It doesn't look too bad and anyway the perch bracket will cover it.

Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #31 on: October 04, 2017, 12:49:08 PM »
Norman, do you know the DP and tooth counts - I'd assume that you probably do ?

Let me know and I'll sort through my collection - if I have what you need you can borrow them for the postage both ways.

(I have both conventional cutters and hobs)

Andrew Mawson
East Sussex

Offline eskoilola

  • Jr. Member
  • **
  • Posts: 34
  • Country: fi
  • OH2GTK
    • Kirppuja
Re: Minnie on the cheap!
« Reply #32 on: October 04, 2017, 01:33:03 PM »
There is a downside in being on an assignment in Germany. Far away from home.
The upside is the weekly flea market. There is a guy who sells machining stuff with prises next to nothing.
I bought 4 kilograms of HSS blanks with 40 euros. They have some dirt on them but that is just cosmetics.

I will go there now on saturday and buy some more, wrap those into post packet and make You happy.
This assuming that the seller is on Lindleystraße. He is always on Schaumainkai but not always on Lindleystraße.
The flea market is alternating between those two locations.

They also sell decent sausages as my grandson demonstrates.



I'll put the pictures of the blanks here now on saturday if the seller was there.
http://www.hfm-frankfurt.de/flohm%C3%A4rkte.html

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #33 on: October 04, 2017, 02:40:03 PM »
Wow, there are generous people on this site! :mmr:
What I need is 20DP to cut 15,20,25,30,50 & 80 tooth gears. I think that single point cutters would be best with my milling machine.

Offline chipenter

  • Hero Member
  • *****
  • Posts: 726
  • Country: gb
Re: Minnie on the cheap!
« Reply #34 on: October 04, 2017, 02:50:07 PM »
Make 20 dp single point cutters out of 1/4" silver steel , very much like a fly cutter only flat .
Jeff

Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #35 on: October 04, 2017, 03:00:03 PM »
Norman, I have all sorts of B&S cutter sets but not 20 DP  :bang:

HOWEVER I do have  20 DP hob as per pictures. 3/4 bore weighs 400 grams
Andrew Mawson
East Sussex

Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #36 on: October 04, 2017, 03:12:19 PM »
OK a bit more trawling through the hob drawers !

Turns out that I have two of the above hobs AND:

A nice little 10 mm bore one that I used to use with my Mikron gear hobber (which is for sale at £1000 if anyone wants it - needs a clean up as been in storage for 10 years)

This little one weighs in a 75 grams  :thumbup:
Andrew Mawson
East Sussex

Offline eskoilola

  • Jr. Member
  • **
  • Posts: 34
  • Country: fi
  • OH2GTK
    • Kirppuja
Re: Minnie on the cheap!
« Reply #37 on: October 04, 2017, 03:32:48 PM »
How is that sort of gear tool used ?
Does it not need the gear rotation to be synchronized with the tool rotation ?
Is it self synchronizing - so as You start it it will automagically (somehow) catch the startpoint on correct phase?

I have seen many videos on people using thread cutter to make gear but nobody shows the very first round around - and nobody certainly shows how it goes all wrong.

And Yes - I know a lot more about datawarehousing than machining. That is the reason I am here - it is fachinating  :med:


Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #38 on: October 04, 2017, 03:35:06 PM »
Andrew Mawson
East Sussex

Offline eskoilola

  • Jr. Member
  • **
  • Posts: 34
  • Country: fi
  • OH2GTK
    • Kirppuja
Re: Minnie on the cheap!
« Reply #39 on: October 04, 2017, 03:48:58 PM »
Essentially yes:

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

In this case one thousand words had more information than one hour of tiresome hobbing videos.

Thanks !

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #40 on: October 04, 2017, 03:50:07 PM »
Am I missing something here? I read an article on making a hob to cut gears and it showed the teeth on the hob being cut straight. It was then used in steps to cut each tooth individually, but also cut a little of the following tooth and preceding tooth. In doing this it shaped the teeth correctly irrespective of the number of teeth on the gear.

Offline eskoilola

  • Jr. Member
  • **
  • Posts: 34
  • Country: fi
  • OH2GTK
    • Kirppuja
Re: Minnie on the cheap!
« Reply #41 on: October 04, 2017, 03:52:10 PM »
I think that helix thing does exactly the same and in fact is more precise. However it needs a special machine to do the hobbing as it does not work in steps but continuously ... i think  :scratch:

The tool is most certainly NOT placed on 90/180 degree angle to get straight tooth.

Edit: Ärgh... In fact ... if I look the tool from side it actually looks like a lot of triangels. So it might actually BE placed on straight angle to get straight teeth....

Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #42 on: October 04, 2017, 04:20:32 PM »
The hob rotates in synchronism with the blank at a ratio suitable to cut the right number of teeth. The hob is then transversed across the blank at a fixed cutting depth. Depending on materials it may take several passes at increasing depths before the full tooth form emerges
Andrew Mawson
East Sussex

Offline chipenter

  • Hero Member
  • *****
  • Posts: 726
  • Country: gb
Re: Minnie on the cheap!
« Reply #43 on: October 04, 2017, 06:10:12 PM »
The hob is also at an angle to match the hobs pitch , you also can't start at the edge of the gear if trying to cut a gear being driven by the hob , I have tried this and bent the mandrill for my hob and totaled the gear .
Jeff

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #44 on: October 05, 2017, 11:41:17 AM »
I have been reading a copy of Model Engineer magazine from 1955 and I came across an article on gear cutting by Martin Cleeve. He said that in his early days he just bought a No 3 cutter and used it to cut gears from 25 to a rack with acceptable results. I might be able to get away with two cutters no3 and no 6. That's not so expensive!

Online awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5529
  • Country: gb
  • East Sussex, UK
Re: Minnie on the cheap!
« Reply #45 on: October 05, 2017, 12:09:12 PM »
Norman,

I seem to recall that you said that this was a display model rather than a working one, in which case it doesn't matter a lot  :med:

Andrew Mawson
East Sussex

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #46 on: October 05, 2017, 12:46:16 PM »
Well I would like to run it on compressed air.

Offline eskoilola

  • Jr. Member
  • **
  • Posts: 34
  • Country: fi
  • OH2GTK
    • Kirppuja
Re: Minnie on the cheap!
« Reply #47 on: October 07, 2017, 11:44:24 AM »
The dude who sells HSS steel blanks was not in the flea market today as I suspected. He will be in the other loaction next saturday.

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #48 on: October 10, 2017, 03:35:24 PM »
I was busy over the weekend, I made the chimney. I cast a piece of aluminium using the lost foam method, what a lot of nasty fumes that produces! It was a terrible casting, barely big enough and full of bubbles. What the heck, it's going to be painted so I can use filler to hide the defects.
The chimney cap was fun, I made it from two pieces of 1/4" brass silver soldered together. I've finally worked out how to use my gas torch, outside of the furnace, without it blowing out. It was an interesting diversion from machining to work out the angles to rough out the two curves, my trigonometry tables from my school days came in handy for that.

Offline NormanV

  • Hero Member
  • *****
  • Posts: 514
  • Country: gb
  • United Kingdom
Re: Minnie on the cheap!
« Reply #49 on: October 10, 2017, 03:41:19 PM »
I fabricated the chimney base rather than buying or making a casting, I was able to do it more quickly than it would have taken to make the pattern. I had to cut a large radius in the base of it and was rather pleased with my setup. I mounted it on a piece of angle on the faceplate, which needed counter balance weights to prevent vibration. I used my 1" square boring bar to hold the cutter, there were no problems with chatter.