3/16 rod

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Master

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Used to get 3/16 steel rod for model boat propeller shafts. Was able to easily drill 1/16 hole and thread 10-32. All rod available now is too hard to drill or tap. Not sure what it was that I bought in the past that was so forgiving.
 

BaronJ

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Used to get 3/16 steel rod for model boat propeller shafts. Was able to easily drill 1/16 hole and thread 10-32. All rod available now is too hard to drill or tap. Not sure what it was that I bought in the past that was so forgiving.
I think you might have your sizes mixed up !
I use 4 mm drill for 10-32 threads and 3/16" is 4.7 mm. A tad too big to put a 10-32 thread on.
 

Master

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I may have misled. Drilled 1/16 inch hole in rod for roll pin, then used 10-32 die to thread the rod for the propeller nut. The particular rod metal bought at the hobby shop was very easy to work. The rod from hardware stores is too hard. I wonder why the difference?
 

Tug40

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I have found good brand welding rod to be fairly precise.
You might go to a welding supply & measure some 3/16 rod.
7018 is pretty good. Or 6013 might be easier to drill & tap?
I was thinking same as BaronJ as per size drill for 10-32.
I use 5/32”bit for 10-32, works for me.
YMMV of course.
 

BaronJ

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Hi Master,

You might find that the issue with the rod is not hardness but over size ! If I'm die threading a nominally 4 mm diameter bar 10-32, I do turn it down to 3.8 mm as I find that it is difficult to start a die on an oversize diameter.

Single pointing I don't bother, as long as the nut screws on without being tight. Even then I've found that running a die down the threads sometimes takes a bit off !
 

GailInNM

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I would suggest that you try 12L14 steel. It available from most any of the online metal vendors such as Online Metals or Speedy metals.
12L14 is very easy to machine. It's only disadvantage is that is is a little more prone to rust than some other alloys, but if you wipe or spray a little oil on it that is not a problem.
 

deverett

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Is mild steel the best material for model boat prop shafts? I would have thought stainless steel would be better for its non-rusting properties.
With that thought, could it have been 303 that was used previously and now it is 316 that is used. 316 tends to be more difficult to work.
I realise that 303 is not regarded as non-rusting certainly not compared to 316, but maybe OK in fresh water.
Dave
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GailInNM

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Dave,
I agree that stainless steel would be a better choice from an engineering standpoint. The thread started is having trouble machining the steels that he has tried so I suggest 12L14 to overcome his machining problems. I have used 12L14 for model steam locomotives and engines for many years without corrosion problems. They are exposed to water both in operation and cleaning. I do wipe the parts down with oil after machining and find that normal lubrication of the parts in operation leaves enough oil on then to give enough protection. I use full synthetic oil for lubrication (Mobil 1 0-20) as it does not evaporate over time or gum up if the model is not run for a long period of time.
 

deverett

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When suggesting stainless steel, I was thinking of exposed propshafts as used in high speed craft. I can see that mild steel in slower vessels such as cargo vessels with enclosed propshafts would be perfectly adequate as you describe, Gail.

Dave
The Emerald Isle
 

SmithDoor

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Stainless steel welding rod .

Note Some local welding suppliers may sell just one rod

Dave

When suggesting stainless steel, I was thinking of exposed propshafts as used in high speed craft. I can see that mild steel in slower vessels such as cargo vessels with enclosed propshafts would be perfectly adequate as you describe, Gail.

Dave
The Emerald Isle
 

comstock-friend

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4mm for 10-32??? Sorry but 3/16" is just right, a 10-32 thread has a 0.190" diameter. Number threads are the number x 0.013 + 0.060. Thus #10 is (10 x 0.013) + 0.060 = 0.190", # 8 is (8x0.013)+0.060=0.164" (maybe Baron's 4mm), etc.

As to material, I find 1144 stress proof about as nice to machine as anything, and great strength.

John
 

bluejets

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I've used 3/16" stainless for donkeys years with no problems.
Bronze bushing at motor end and water lube bushing in the water.
Even used to make my own flexi-shafts with stainless prop end shaft and again, leaded bushings.
 

GailInNM

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John (comstock-friend),
I like 1144 also and have used quite a bit of it as it machines well and has very little distortion from machining.
Unfortunately I don't know of any common source of it under 1/4 inch diameter and the OP needs 3/16 diameter. If anyone knows of a source under 1/4 inch I would like to know.
 

SmithDoor

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3/16" is 0.1875 and ,#10 screws is 0.190" that only a different of 0.0025".


Dave

4mm for 10-32??? Sorry but 3/16" is just right, a 10-32 thread has a 0.190" diameter. Number threads are the number x 0.013 + 0.060. Thus #10 is (10 x 0.013) + 0.060 = 0.190", # 8 is (8x0.013)+0.060=0.164" (maybe Baron's 4mm), etc.

As to material, I find 1144 stress proof about as nice to machine as anything, and great strength.

John
 

Master

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Thanks to all that have given me inputs. Found a 3/16 stainless steel rod at a hobby shop. Used a 10-32 die and it threaded very nicely.
 

bluejets

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Thanks to all that have given me inputs. Found a 3/16 stainless steel rod at a hobby shop. Used a 10-32 die and it threaded very nicely.
Either it's crappy stainless or your die is now useless (if carbon steel)
Only way you'll run a thread on any stainless worth it's salt is if the die is HSS.
 

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