Replacement gear required

[Richardsth]

Does anyone know within the Norfolk area where I can get a spur gear made up for my old Ridgeway morticer? or Failing that, where I can get a replacement from? I foolishly stripped the teeth trying to mortice oak with a blunt auger, so consequently something was going to give.

I don’t want to have to scrap it, so ideally I’d like to get it fixed.

chhers Rik

 

[MARK.B.]

Blimey did you have Weetabix for breakfast

 

[flh801978]

If all else fails i can make one for you but it may take buying a gear cutter depends on the size

 

[Richardsth]

If all else fails i can make one for you but it may take buying a gear cutter depends on the size

hmmmm. Sounds expensive for a four inch gear! I think that it maybe destined for that knackers yard.

 

[Doug71]

I bought an old Record Power WM Ridgway morticer (same model?) which I found had the same problem.

A lad I knew came and took a few measurements of the pitch etc and ordered one from somewhere, think he charged me £40 for fixing it.

I will dig out the morticer tomorrow and see if it looks the same and try to track the lad down to see where he got the gear from.

 

[Richardsth]

I bought an old Record Power WM Ridgway morticer (same model?) which I found had the same problem.

A lad I knew came and took a few measurements of the pitch etc and ordered one from somewhere, think he charged me £40 for fixing it.

I will dig out the morticer tomorrow and see if it looks the same and try to track the lad down to see where he got the gear from.

I figured that most of the old English MortIcers shared commons parts like gears, but do you think that I can find one? It will be great if he can get this one fixed, or at least get a replacement part.

 

[Sideways]

To me there looks to be a very substantial amount of work in fixing that. To the point where I would think it's easier to replicate than to repair. If you can find a replacement for £40, that's a huge saving over what I'd expect to pay for a custom made gear.

 

[mikej460]

I take it you've searched t'internet Spur Gears (gearsandsprockets.co.uk)

 

[baldkev]

Ive got a ridgeway too.... the return spring on mine was broken when i got it. I ordered one off ebay ( guessing the required size ) but its not quite strong enough, still havent ordered a thicker one!! maybe I'll do it now

 

[Devmeister]

Contact Keith Rucker at vintage machinery.com and check out his YouTube tube channel.

Check out David Richards on YouTube. He had the old steam powered machine shop.

I would help but my so called girlfriend filed a common law against me and I am struggling with that now. May have to find a new place to live. Women Aghhhh!!!

Otherwise I would knock this out in a hurry! Make it from 8620 steel and case harden with kasenite. No need to have a gear jibber do it as the gear does not turn fast enough. An old milling machine and dividing head is just fine.

 

[J-G]

I can count the teeth and deduce that it is a 40 tooth but with no 'scale' or information about the OD, it's impossible to determine the DP or MOD.

Add to that the fact that it looks as though the [boss] originally had two cross holes, one (or both) of which may well have been threaded, and you are on a hiding to nothing as far as getting someone here to even determine whether it might be possible to assist.

I notice Richardsth (message #4) has mentioned [ a 4" gear ] so he may know something that I don't, If it is in fact 4.2" OD then it would be a 10DP which is 4" PCD but that still isn't anywhere near enough information to source a commercial replacement. I know that it's beyond my capacity - I can handle up to 20DP - - - at a push! - - - but prefer working at 0.5MOD

 

[Devmeister]

Check the internet or machinists handbook. David Tichatds covers some of this in his YouTube videos on the old steam powered machine shop.

The equation for DP establishes a relationship between the pitch circle and the OD. If you have the OD and tooth count you can compute the DP.

As an older woodworking machine, the likelyhood of it being a fellows style stub tooth is unlikely! Also, I will bet you that it’s a. 14.5 degree pressure angle. The 20 degree pressure angle came out later and was not that popular in woodworking machines. Mods are a metric version of DPs.

The tooth design is involute. That is a special math equation that spans the tooth. It’s the same for mods or DPs. The notion of DP is nothing special. You can’t put a massive tooth on a small gear and there is no point in using fine teeth on a bull gear. So DP was an agreed on compromise for establishing the size of a practical tooth.

 

[Devmeister]

Look up The old steam powered machine shop on YouTube with Dave Richards.

According to Henry ford, the DP is equal to (number of teeth + 2)/blank diameter.

So a 40 tooth gear with a 4 in OD would have a DP of 10.5. Unlikely!

But a 40 tooth gear having a 4.25 in OD would yield a DP of 10.

Standard cutters come in groups or sets of 8. A 40 tooth gear will need a #3 cutter.

The pressure angle is either 14.5 or 20 degrees. Because of its age and application, my money says it’s 14.5 degrees.

As mentioned reach out to Dave Richards. I would do it but I am unable to take this on right now. In a few months I may be able to. Dave and I both have the cutter already.

 

[Doug71]

@Richardsth Is yours the same model as this?

This is the new gear inside, I think it was ordered online from somewhere.

I'm sure this mortiser has been messed around with because it wouldn't come from the factory looking like this

Like Kevs the spring needs some attention on mine as the handle can drop down if you aren't careful.

Would be interested if anyone has a photo of what it should look like inside?

 

[eribaMotters]

Have you tried looking at the Startrite STM25 morticer? I also think Axminster sold a rebadged version of the Startrite.
STE STM25.pdf (dm-tools.co.uk)

Colin

 

[baldkev]

Hi doug, I found a photo of my rear

The last photo shows the ( i believe ) original spring. Someone had replaced it with a longer spring..... obviously not einstein..... i got a 3mm x 120mm with an outside coil diam of 25mm, which works a bit, but the chisel can and does suddenly drop sometimes. Ive ordered a 4mm x 120 and a 4mm x 100mm spring off ebay ( about 10 quid for the pair )

 

[Richardsth]

I don’t know whether this is relevant or not, but I can see a number 420 stamped on it.

 

[J-G]

But a 40 tooth gear having a 4.25 in OD would yield a DP of 10.

No it would not! I've already pointed out that IF it is 4.20" OD then it is 10DP if it were 4.25" OD then it would be 9.88235294117647 DP (42 / 4.25) much less likely than your suggestion of 10.5 DP.

Somewhat more important than the OD is the Pitch Diameter which, for a 40T 10DP gear, is 4". The OD could be larger or smaller than the ideal 4.2" but that would mean that the Addendum had been increased or decreased which may have an impact upon how the mating gear (or rack) mesh (or bind).

Incidentally - since it seems that you are still at the learning stage with regard to gearing - DP stands for Diametral Pitch.

 

[J-G]

I don’t know whether this is relevant or not, but I can see a number 420 stamped on it.

Trying to second guess what the manufacturer wanted to convey with that marking is futile! Unless you are privy to the makers technical information.

It might mean 4.2" Dia - but it might also mean 4" Pitch Dia. and 20º PA (Pressure Angle)

 

[deema]

J-G has helped me on another thread, his depth of knowledge and understanding of gears is IMO one that you should listen to very carefully.