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plunger
08-30-2017, 05:56 PM
Are these cutters possibly useful for the home shop machinest. I would like to try cutting some gears ,just too ignorant to know if this is what I need or not.
https://www.banggood.com/M4-PA20-Inside-Bore-Diameter-22mm-1-8-HSS-Involute-Gear-Milling-Cutter-p-1009851.html?rmmds=detail-bottom-viewalsoview

Magicniner
08-30-2017, 06:06 PM
It's a set of cutters for MOD 4 gears, there are sizes for number of teeth here - http://www.hpcgears.com/pdf_c33/23.68-23.73.pdf

A 10 tooth MOD 4 Gear will be 52mm OD, that's fairly big to me but may suit your needs?

- Nick

plunger
08-30-2017, 06:45 PM
It's a set of cutters for MOD 4 gears, there are sizes for number of teeth here - http://www.hpcgears.com/pdf_c33/23.68-23.73.pdf

A 10 tooth MOD 4 Gear will be 52mm OD, that's fairly big to me but may suit your needs?

- Nick

I was hoping to cut a twenty tooth gear on a 25mm od blank. Its for a small ring roller.

Bob Engelhardt
08-30-2017, 06:46 PM
I used one of theirs to cut a couple of change gears for my lathe. Worked fine; caveat - I made aluminum gears.

Also, be sure to note that the bore is 22mm! I had to make a new arbor for my horizontal mill.

Paul Alciatore
08-30-2017, 09:33 PM
Yes, those are gear cutters. First, I do not think that seller is selling a set of eight for that price. I think he is selling each of them for that price and the full set would cost around $120 or more. For 20 teeth you would only need the #4 cutter in the set which cuts between 21 and 25 tooth gears.

There is no way of knowing the quality of those cutters. You pay your money and you take your chances. But they are probably a good way to get a start cutting gears.

But, you say you want a 25mm (outside?) diameter gear with 20 teeth. Those cutters are for module 4 size teeth (M4). They would cut only about 4.25 teeth on a blank with a 25mm outside diameter, not 20. For 20 teeth with these M4 cutters you would need to have a blank that has a OD (outside diameter) of about 88mm.

If you want 20 teeth on a gear with a 25mm OD, you would need a cutter for metric module 1.136... I don't think you will find that exact module and you will need to settle on M1 or perhaps M1.25 if you can find it. A M1 cutter will produce a 20 tooth gear on a blank with a 22mm OD.

The applicable formula here is

M = OD / (N + 2)

Where:
M = Metric module
OD = Outside diameter of gear
N = Number of teeth

The (N + 2) term is due to the fact that the module is based on the PD (pitch diameter), not the OD. So the PD is smaller than the OD and the standard tooth geometry dictates the +2 factor.

How are you going to do the dividing?




I was hoping to cut a twenty tooth gear on a 25mm od blank. Its for a small ring roller.

plunger
08-31-2017, 01:13 AM
Yes, those are gear cutters. First, I do not think that seller is selling a set of eight for that price. I think he is selling each of them for that price and the full set would cost around $120 or more. For 20 teeth you would only need the #4 cutter in the set which cuts between 21 and 25 tooth gears.

There is no way of knowing the quality of those cutters. You pay your money and you take your chances. But they are probably a good way to get a start cutting gears.

But, you say you want a 25mm (outside?) diameter gear with 20 teeth. Those cutters are for module 4 size teeth (M4). They would cut only about 4.25 teeth on a blank with a 25mm outside diameter, not 20. For 20 teeth with these M4 cutters you would need to have a blank that has a OD (outside diameter) of about 88mm.

If you want 20 teeth on a gear with a 25mm OD, you would need a cutter for metric module 1.136... I don't think you will find that exact module and you will need to settle on M1 or perhaps M1.25 if you can find it. A M1 cutter will produce a 20 tooth gear on a blank with a 22mm OD.

The applicable formula here is

M = OD / (N + 2)

Where:
M = Metric module
OD = Outside diameter of gear
N = Number of teeth

The (N + 2) term is due to the fact that the module is based on the PD (pitch diameter), not the OD. So the PD is smaller than the OD and the standard tooth geometry dictates the +2 factor.

How are you going to do the dividing?

Thanks for that . I need to try absorb that. I have a dividing head,but that too is a learning curve.I wonder for my application if I cant just fly cut it in brass.
Its the george Thomas ring roller

Bob Engelhardt
08-31-2017, 07:29 AM
...
Its the george Thomas ring roller

I'm not familiar with that roller, but in general rollers use a lot of torque - brass might not be up to it.

Frank K
08-31-2017, 06:18 PM
I've purchased complete sets of 8 cutters on eBay shipped directly from China for about $65. Of course, not the greatest and had to clean off a bunch of surface rust but since I only cut aluminum and Delrin gears they worked just fine. I don't know if I would even attempt cutting steel blanks with them but they suited my purposes.

sansbury
08-31-2017, 07:43 PM
I've purchased complete sets of 8 cutters on eBay shipped directly from China for about $65. Of course, not the greatest and had to clean off a bunch of surface rust but since I only cut aluminum and Delrin gears they worked just fine. I don't know if I would even attempt cutting steel blanks with them but they suited my purposes.

+1. The worst thing with the set I got was they were clearly mixed from old stock, so I needed to make two different arbor sizes to use them all. Haven't tried brass yet but they worked fine on 6061.

cuslog
08-31-2017, 10:48 PM
I purchased a 16dp set of the ebay / china ones -- cut 4 or 5 different gears in 3/4" plate / mild steel -- worked fine, you could see that one was getting a bit dull (pushing up larger burrs) after cutting about 160 teeth.

RichR
09-01-2017, 12:40 AM
Thanks for that . I need to try absorb that. I have a dividing head,but that too is a learning curve.I wonder for my application if I cant just fly cut it in brass.
Its the george Thomas ring roller

So you're going to grind the tooth form into a piece of HSS and mount it in a fly cutter? Then skip the brass and make it out of steel. Just make sure
you measure the effective diameter of the cutter and calculate an appropriate RPM so the cutter doesn't dull prematurely.

plunger
09-01-2017, 01:21 AM
I am trying to gear the rollers together on this mini ring roller. The bigger the teeth the better as it needs to compensate for about 3mm maximum thick material.I wonder what the biggest teeth on a small gear could be. ?

oldtiffie
09-01-2017, 02:59 AM
I purchased a 16dp set of the ebay / china ones -- cut 4 or 5 different gears in 3/4" plate / mild steel -- worked fine, you could see that one was getting a bit dull (pushing up larger burrs) after cutting about 160 teeth.

And that is about the first and only time that I am aware of that anyone has mentioned the need for a tool and cutter grinder - or a functionally simple one - to sharpen the cutter/s.

Norman Bain
09-01-2017, 06:49 PM
I am not clear on the layout off the gears. Are their two gears or 3 (or 4 with idler)?

If the gears are required to "separate" in order to allow a pair of rollers to move relative to each other as the rollers are adjusted for various stock size and/or roll diameter then the gears need to be chunky. Most of the low-end commercial units work this way ... chunky gears that mesh badly.

It may assist to post a photo of a diagram of your intended design.

Illinoyance
09-01-2017, 08:02 PM
The Thomas rolls use 4 gears.

plunger
09-02-2017, 02:55 AM
I am not clear on the layout off the gears. Are their two gears or 3 (or 4 with idler)?

If the gears are required to "separate" in order to allow a pair of rollers to move relative to each other as the rollers are adjusted for various stock size and/or roll diameter then the gears need to be chunky. Most of the low-end commercial units work this way ... chunky gears that mesh badly.

It may assist to post a photo of a diagram of your intended design.

Yes I need four chunky badly meshing gears.I am hoping to have a size to copy because I cant cad draw or do the maths to work out if a home designed gear would work. I am likely to make a gear with 18 and a half teeth.

Bob Engelhardt
09-02-2017, 09:46 AM
Yes I need four chunky badly meshing gears....

I made slip rolls using that concept - IIRC, it was a Gingery Jr design. It was a royal pain to get the gears to work over the range of roll spacing. Lots of very tedious grinding of gear teeth.

Later I saw pictures, but no details, of rolls that used links to connect the rolls. The links are on both ends and out of phase by 90 degrees. It only had 1 adjustment, though, and I don't know how well that would work.

https://i.imgur.com/4SZZxsq.png

Bob

Paul Alciatore
09-02-2017, 07:49 PM
I would think that Bob's link connected rollers would be a lot easier to make and more robust in use.

Norman Bain
09-02-2017, 10:29 PM
EDIT: Post content removed as it would not have successfully achieved what I wanted to display ... was rubbish.

plunger
09-03-2017, 02:56 AM
I made slip rolls using that concept - IIRC, it was a Gingery Jr design. It was a royal pain to get the gears to work over the range of roll spacing. Lots of very tedious grinding of gear teeth.

Later I saw pictures, but no details, of rolls that used links to connect the rolls. The links are on both ends and out of phase by 90 degrees. It only had 1 adjustment, though, and I don't know how well that would work.

https://i.imgur.com/4SZZxsq.png

Bob

This link looks interesting. My ring roller works on a slightly different principle. Two of the three rollers need to be adjustable. It does not work like a pyramid type. In your type if the two rollers shown could be adjustable (3mm max) would it effect the linkage. That looks like a far simper method.
Having a closer look atthis it wont work as in mine the two rollers need to rotate opposite to each other.

RichR
09-03-2017, 10:23 AM
EDIT: Post content removed as it would not have successfully achieved what I wanted to display ... was rubbish.

I saw that post. Too bad you removed it, I found it interesting.

CCWKen
09-03-2017, 11:57 AM
On my 3-n-1 roller, the front upper and lower are arranged one on top of the other with the top adjustable for material thickness. These two rollers are joined by gears so material thickness is limited to sheet products. The rear roller is independent and has considerably more adjustment to change the amount of "roll" in the material. The rear roller moves on a tangent to the front top roller instead of to the center of the front rollers.

The roller in the photo above appears to be made like the pipe/tube rollers.

Norman Bain
09-03-2017, 04:59 PM
I saw that post. Too bad you removed it, I found it interesting.

Panic set in about 20 minutes after I had posted it. I realised that the text I had attached to the post was not a match for the reality.

I will post it again here with modified text that more suits the aims.

Short story, This mechanism does allow the gears to stay correctly meshed during adjustment and also make the two pinch rollers to travel in same direction.

http://downloads.purposebuilt.com.au/NJB/SheetMetalRoller/EndView.png

The pinch rollers are the big top and bottom ones. The form roller is only seen in part of the side view.

The top pinch roller can be lowered and raised a goodly way as its arc travels around the idler gear that it is immediately next to; controlled by an arm that is on the same axis as the smaller idler gear.

The larger idler gear can be any size and number of teeth.

In this scenario the pinch rollers are 35mm and the smaller gears are Module 3 with 18 teeth.

The layout of the gears (with the wider gear covering both sets) allows the top pinch roller to come down and meet the bottom pinch roller without clashing the gear set.

http://downloads.purposebuilt.com.au/NJB/SheetMetalRoller/SideView.png

The form roller (in this scenario) is on controlling bar rather than being held at the ends. The form roller has considerably smaller diameter than the pinch rollers.

NOTE: The form roller is only shown in the side view picture.

The aim of the form roller being on a controlling bar is to allow the form roller to be moved right up into the mating of the pinch rollers; thus allowing a sheet to be rolled at exact the diameter of the pinch roller and also to reduce that "straight" bit that is caused by any gap between the pinch rollers and the form roller.

plunger
09-03-2017, 06:14 PM
Panic set in about 20 minutes after I had posted it. I realised that the text I had attached to the post was not a match for the reality.

I will post it again here with modified text that more suits the aims.

Short story, This mechanism does allow the gears to stay correctly meshed during adjustment and also make the two pinch rollers to travel in same direction.

http://downloads.purposebuilt.com.au/NJB/SheetMetalRoller/EndView.png

The pinch rollers are the big top and bottom ones. The form roller is only seen in part of the side view.

The top pinch roller can be lowered and raised a goodly way as its arc travels around the idler gear that it is immediately next to; controlled by an arm that is on the same axis as the smaller idler gear.

The larger idler gear can be any size and number of teeth.

In this scenario the pinch rollers are 35mm and the smaller gears are Module 3 with 18 teeth.

The layout of the gears (with the wider gear covering both sets) allows the top pinch roller to come down and meet the bottom pinch roller without clashing the gear set.

http://downloads.purposebuilt.com.au/NJB/SheetMetalRoller/SideView.png

The form roller (in this scenario) is on controlling bar rather than being held at the ends. The form roller has considerably smaller diameter than the pinch rollers.

NOTE: The form roller is only shown in the side view picture.

The aim of the form roller being on a controlling bar is to allow the form roller to be moved right up into the mating of the pinch rollers; thus allowing a sheet to be rolled at exact the diameter of the pinch roller and also to reduce that "straight" bit that is caused by any gap between the pinch rollers and the form roller.

We did you see this drawing? it makes sence to have the idler and one top big roller on the same banjo arm. It seems then that the mesh should be less of a problem.

Norman Bain
09-03-2017, 07:50 PM
We did you see this drawing? it makes sence to have the idler and one top big roller on the same banjo arm. It seems then that the mesh should be less of a problem.

If it is me you are asking the question of, I advise that the images (as screenshots) are taken from a CAD project that I was tinkering with a couple of years back.

The CAD project (in Alibre) is pretty flexible and I would consider modifying it to your aims if you were clear in which direction you wanted to take it.

Suggested is you copy the image into Paint and write (scratch away) on that with the Paint tools available; then post the resultant image here for us all to comment on.