Tiny IC gear question

[kcmillin]

I am seriously thinking about starting work on the "Tiny IC" designed by Arv. (PutPutMan)

The gears specify to be 48 DP but I am not sure which pressure angle to use. 14.5 degree or 20 degree.

I have found some involute cutters in 14.5 and I also found a gear hob in both pressure angles.

here is the link to it
http://www.gearprosinc.com/catalog/index.php?main_page=product_info&products_id=55&cPath=3_4

I have a few questions about using the hob.

1. How do I know how deep to make the cut.
2. Does this type of hob automaticly move the blank, or do I use an indexer?
3. For light cuts do I have to make an arbor with a keyway?
4. I assume the gear hob replaces the set of 8 involute cutters, right?

In my head the hob is the way to go, but is there any disadvantages to it.

Kel

 

[putputman]

Kel, I'm glad to see some interest in the Tiny I.C. I still run mine more than any of my engines.

I used 14.5 deg cutters for my engine. # 4 & 7.

I am not familiar with that type of hob but it appears that the gear must be driven. The teeth look like they spiral up the hob.

As far as depth of cut, Marv's gear program will give you all the information you will need to cut the gears with a conventional cutter and I assume it would be the same for a hob.

 

[kcmillin]

Thanks Arv, I was 75% sure it was 14.5. Know I know.

I am still considering the involute cutters. I am looking for a good used affordable set. Or a new affordable set. currently I find them to be about $360 American for a complete set. I am a stickler for a complete set, but I might just get the two I need for this engine and add to it from there. I can see many uses for these and the 48dp size is perfect for model engines.

I wish they sold single point gear cutters, perhaps an indexable type. Or do they, and I just don't know about them?

Anyway, Jerry and Brian's post on single point cutters is still in the back of my mind.


One more question. Can denatured alcohol be used as a fuel? If so, what type of lube is required?

Kel

 

[mocaquita]

Hi,
The hob you are looking at is meant to be used on a hobbing machine where the gear blank is rotated constantly at a controlled rate. It does have a spiral to it and with this hob one rev of the hob will pass two gear teeth. Will it rotate a free wheeling gear blank by itself? I don't know, never tried it. I've only used this type of hob on a gear hobbing machine. Depth of cut is marked on the hob. WD (Whole Depth) .0478". It will cut practically all number of teeth gears.

Dave

 

[rklopp]

Travers Tool sells 14.5-deg and 20-deg 48-DP cutters. I bought the #2 and #4 cutters for 14.5-deg. They were about $27 apiece. They are Chinese, but seem to hold up well and make reasonably accurate gears. I find I have to go a tad deeper than handbook depth and knock a tad off the gear ODs, but the end result is pretty good meshing at handbook center distance. I also bought the same size cutters from Victor Machinery Exchange. They wanted around $45 each. I wish I'd found Travers as a source first. The runout on the #2 Victor cutter was really bad. The rest are OK. They have 7/8" arbor holes, and I am running them on a horizontal mill with a conventional arbor and overarm support.

I am cutting six each 60-tooth and 30-tooth gears for the cam drive of a set of six Upshur Twins. That a lot of teeth. The material is LaSalle ETD-150, which is a free-machining 4140. I go slow (60 ft/min) and flood with cutting oil. The #2 cutter is close to due for resharpening.

 

[kcmillin]

Thanks rklop.

I was looking at the Victor, but I am most definitely going the Travers rout.

There listing are a little vauge. I would like to confirm my suspicion.

By 48" they mean 48dp, Right? :shrug:

And the number of the cutter I assume is hidden in the part number. The third digit in the second set of numbers?

http://www.travers.com/skulist.asp?...evel3+id+30188&AttribSel=Pitch+Diameter='48"'

Kel

 

[philt214]

I purchased two 48dp gear cutters from Travers for the Powerhouse IC engine I was building. They worked fine. There was a time when Wholesale Tool had 48dp cutters for cheap, but they are gone. The price of cutters has gone up probably more than most tooling so that Travers now has about the best price. You might find something on Ebay, but I rarely see anything as small as 48dp cutters. Buy what you need.

 

[rklopp]

Yes, Travers mislabels 48 DP as 48". Go figure. You are correct about the cutter number being hidden in the 3rd digit of the second set of numbers in the catalog number. It's all pretty clear in the paper catalog.

 

[precisionmetal]

kcmillin,

A hob IS the way to go, unfortunately a hobbing machine is required to use one as DaveB mentioned.

When cutting gears (regardless of method used) it's always best to measure them "over wires" rather than simply relying on a "depth of cut" from touching off on the OD (at least if you're serious about getting the backlash exactly where you want it)

If there's any assistance I can offer, fire away if you have questions. (see my post titled: "Gears" in the Specialist forum here).

PM

 

[crankshafter]

kcmillin
Have a look at this hobs from ARCeurotrade.

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Gear-Hobs

Ooor why not make your own?

Best reg.
CS