Bending rolls

[Don1966]

Hi Rich, the 16 DP would work for a 22 tooth 14.5PA gear at 1.5" diameter. The 20 DP would work for a 28 tooth 14.5PA gear at 1.5" diameter.
Check in plans and drawings for my calculation sheets on gears.  http://www.modelenginemaker.com/index.php/topic,4860.0.html

Don

[Firebird]

Hi

Thanks Jason and Don, all saved and printed. 

When I said I have no experience of gear cutting thats not quite true. A while back I mastered (well mastered isn't quite the right term, managed would be better) cutting T5 timing belt gears. I don't possess a dividing head so did it on a rotary table. I used gear sizes that were easily divisible into 360°. On that basis I would have to go for 20 teeth, but the 16DP cutter will only do 21-25 or up the tooth number to 24. What do you think? I'll go over to ebay and see how much cutters cost as to whether I can justify the expense for a one off job. I'll report back later.
Cheers

Rich

[Jasonb]

As the gears are not going to be whizzing around I should think you could get away with using the 21T to do a 20T gear. Best thing would be to make the gears first then measure the actual ctr distance by meshing two together. The two on the rollers will never be mexhing correctly with the B gears anyway.

May also be worth looking for cheap gears on e-bay, I picked up a set of 2:1 bevels in MOD 1.5 for £6 delivered and they were hardened too.

[Firebird]

Hi Jason

That sounds good, 20 tooth. Involute cutters are around £24.00 for a new one so considering I need 4 gears anyway thats not a bad price but better if I can get away with a borrowed one.

Cheers

Rich

[PStechPaul]

Maybe use some of these for $3 each. Can't hardly buy material for that!
 
http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=TM03MEC4624

These mate to it, also 10 DP, and also $3:
http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=TM03MEC4623

[Firebird]

Hi Paul

That is cheap, if they were available in the UK I would buy some anyway. I haven't found anything like that on ebay.

Cheers

Rich

[Jonfb64]

Hi Rich

Take a look at Myfordboy's video. In one of them he rolls a steel rim for an aluminium flywheel you can see the crank driven rolls that Ian S C mentioned don't  know if they are the same rolls. The steel he's rolling looks about 1/4 inch 3/4 inch wide.
I think it was for his hit and miss engine build.

Jon

[Firebird]

Hi

Thanks Jon

First of all I'm not sure that this topic should continue in the Help section  Moderators please feel free to move it to the tooling section or I could start a new topic over there 

As part of my post op recovery programme a little shed time has been prescribed, just a little tidying and light work to get me back in the swing of things 

So I had a look at what was in the material department. This is what I came up with



Unfortunately no steel plate but the aluminium should be rigid enough.

Sorry about the mix of imperial and metric measurements, I'm just measuring what they happen to be

Starting at the back the piece of ally 7" X 5" X 5/8" should make the end plate.
The piece of ally 7" X 8" X 25mm will make the gear/handle end. I figure thats the end that will have the most effort applied, the other end just needs supporting.
The piece of ally 9 1/2" X 40mm X25mm will make the brace bar
A length of 38mm steel bar for the rolls
A short length of 1 1/2" steel bar, enough to make 4 gears
A bronze bush 1 1/4" OD X 1" ID. Enough to make 2 bushes for the gear end
A bronze bush 20mm OD X 15mm ID. Enough to make 2 bushes for the idler gears
A 25/32 reamer, the only large size reamer I have (origin unknown) For reaming the roller bushes in the end plate
A piece of 1 5/16 brass to make the roller bushes. I don't have any more usable bronze so brass will have to do

Unfortunately the large ally plate has some unwanted holes. I have turned some slightly oversize ally plugs





Pressed them in





In the mill to have a light skim. Its a little to large to do all in one go so had to be turned round.



Looks better



Back indoors now for a rest

Cheers

Rich

[Jo]

Moved 

Jo

[Firebird]

Thanks Jo 

Cheers

Rich

[Firebird]

Hi

Well good old Julian turned up with the gear cutters and an arbor



Unfortunately the arbor is a 2MT threaded for a draw bar which won't fit my X3 which is an R8. So todays effort went into making an arbor. The biggest R8 collet I have is 3/4" so I managed to find a bit of 3/4" round steel bar. Another bit of steel in the lathe is faced and bored to .746



Cross drill and tap 6mm



Chop off in the bandsaw



The 3/4" steel bar is pressed in



Drill into the steel bar through the previously tapped hole



Fit a grub screw. It probably won't need the grub screw, the bar was a good tight press fit but it definitely won't move now



Using the 4 jaw to make sure it runs true



Turn the boss making sure its exactly 1". drill and tap 6mm



The gear cutter has a key way, it should be square but I figured for a one off round will do

Set up in the mill, use a 1/4" end mill to remove the edge then drill down 1/4"



Fit a short length of 1/4" silver steel ( drill rod)



Face another bit of steel for the cap, dish out and drill through 6mm

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That should do

Cheers

Rich

[Jo]

Rich, I would advise you don't use the key way: if it jams with out a key the cutter will spin, with a key it will keep turning and probably damage your piece  .

Jo

[Firebird]

Hi Jo

Thats a good point, thanks  I might not be able to get it out though, I made it a press fit.

While we are on the subject of the gear cutting, when I made the worm wheel for my rotary table I cut it first with a slitting saw. Is it worth cutting the gear blanks with a slitting saw first,

Cheers

Rich

[Jo]

Not sure what you are getting at Rich.

Those size gear cutters will cut full tooth depth on a single pass. Just make sure the blank is nice and solid and that the cutter will not catch your dividing/indexing head at the end of the cut.

Jo

[Jasonb]

No need to do a gash cut first as its not like hobbing where you need something for teh hob to engage in. Just a single pass if your mill is upto it.