Hey, another poppin flame licker with belt driven fan

[kcmillin]

Well I completed one flame licker, and I want to build another one. This story may seem familiar, as Nick and I have decided to build the same engines back to back. At the same time!! Our designs may differ slightly, at least mine will. I am too afraid to use any tap smaller than 4-40. the thought of breaking a teeny tap in a part I worked really hard on frightens me. So I will replace all screws where I can with either 4-40 or some other method of fixing things together.

More to come soon.

kel

 

[cfellows]

Kel,

Strangely enough, I've broken a lot more 4-40 taps than smaller ones. As a matter of fact, I think I have broken more 4-40 taps than any other. I use 2-56 taps pretty regularly and don't think I have ever broken one.

Chuck

 

[kcmillin]

Chuck,
Whats your secret? Do you use a tapping fixture of sorts? Or am I just being to apprehensive about small taps because of my past experience with 4-40. I suppose it may be time to get on the "teeny tap horse" and ride.

kel

 

[cfellows]

Chuck,
Whats your secret? Do you use a tapping fixture of sorts? Or am I just being to apprehensive about small taps because of my past experience with 4-40. I suppose it may be time to get on the "teeny tap horse" and ride.

kel

I have a small tapping guide that I made some years ago. I use it for all taps 8-32 and smaller. I hate tapping more than any other part of machining, probably because I'm a little impatient and tapping requires a slow, methodical process. Here's a picture of my tapping guide. To get an idea of size, the chuck is a 0 - 3/16" size. The base is a piece of 4" aluminum channel, the vertical column is 1" aluminum rod, and the arm holding the spindle is something I picked up at a scrap yard. I think that's a 4-40 tap in the picture.

 

[doc1955]

I think I have to agree with Chuck I have broken more 4-40's than anything smaller it maybe I'm over confident with the 4-40 and am more careful with anything smaller. When a smaller tap starts to get dull it goes by the way side before it has a chance to upset me. So far I've too have been pretty lucky an don't remember breaking any smaller taps.

 

[cobra428]

I find this to be a very handy item. Drill hole pattern. go back with this. Perfectly straight taps

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=5810267&PMAKA=325-5179



Tony

 

[kcmillin]

I guess I should jnust do it. That tapping fixture is nice, I might convert my old drill press for this task.

Doc, how is the weather in Jamestown, neighbor? I live in Bismarck.

kel

 

[kcmillin]

Tony,
Ive seen those before, but I am not sure how they are used.

Do you have pictures of them in action?


kel

 

[cobra428]

kcmillin

I use it the mill this way I know I'm perpendicular. Tip is spring loaded and as you see goes into the little hole in the back of a tap wrench

Tony

PS also good in the lathe

 

[doc1955]

I guess I should jnust do it. That tapping fixture is nice, I might convert my old drill press for this task.

Doc, how is the weather in Jamestown, neighbor? I live in Bismarck.

kel

Don't know can't see outside I'm at work right now its been cold same as there. I have a lot of relatives in Bismarck.

 

[dreeves]

Im with all you guys. I have broke several 4-40 taps but none of the small ones even down to 0-80. I use a spring center in the mill to tap holes in place.

 

[mklotz]

Here are some suggestions from an older post of mine...

http://www.homemodelenginemachinist.com/index.php?topic=464.msg2829#msg2829

 

[NickG]

I will have to take a view on the tapped holes as I don't have the sizes called for. I have BA and small metric but I only have ba screws etc. The 2-56 seems to equate to about 8ba by looking at the clearance size so I'll be using 8ba for those. Trouble is, I remember from my rocking engine I think my 8ba tap is blunt! May have to buy either some new screws or a tap!

Can't wait to see each other's progress on this one, we should be able to help each other along the way.

Nick

 

[rake60]

Don't be afraid of those little taps Kel.
Their depth of cut isn't as proportionate to their core diameter as
larger taps usually are.

I had a bad experience in my early model building days with a 2-56 tap
in aluminum. So, two years ago I bought a box lot of 12 assuming that would
be a normal need for me.

After 2 years I am down exactly 4 pieces from that box lot.

Three of them were retired because I felt I had gotten enough service out of them.
The forth was indeed broken off in an aluminum engine cylinder. That cylinder head
has a little piece of hex stock super glued over hole with the broken tap in it.
No one will ever know which one that is.

Rick

 

[kcmillin]

haha, I like the super glue trick

kel

 

[rake60]

haha, I like the super glue trick

kel

Oh, I have more than one of those!
:-X

Rick

 

[hobby]

I do most of my tapping 4-40's right in the mill drill chuck.

As the tap advances the quill pulls down.

 

[Deanofid]

I'm sure I've broken more 4-40 than the smaller sizes, too. I doubt very much that it is something to do with the 4-40 size, but that I probably tap 10 times as many in that size than with the smaller taps.

Just go slow at it, Kel. Use good quality taps, clean the hole after each full rotation, break the chip about every 1/3 rotation, use the appropriate tapping lube. If you're tapping aluminum, paraffin wax works very well. Brass needs no lube. Steel needs a liquid lube made for the purpose.

Dean

 

[NickG]

I did the same on my rocking engine and put a dummy bolt in the frame - luckily I hadn't opened those out to clerance size yet so was able to tap that hole rather than give it the clearance drill.

I hate tapping in the mill as there is no feel of when it's got to the bottom and the return spring of the quill is enough to strip threads in my opinion, especially when getting near the top one the way back out. So I just use the chuck as a guide lightly nipped around the tap shank and let it slip in that using a normal tap wrench as well.

Seems to work reasonably well most of the time.

Nick

 

[kcmillin]

Wow, I might have to change the name on this thread to, "Dont be scared, its only a tap".

Thanks for the encouragement guys. There should be some small taps on order in my future.

Anyway, I have been studying the pland for a couple days now, and am ready to start the build. I have a 1 x 2 bar of aluminum I will use for the "standard". This is what the plans call for. although a few dementions wil need to be changed to accomodate my bearing size. I plan on making it a "Full Floating design" by putting bearings on the crank journal, and valve shaft.
(no time to get to the shop, there is a break in the bitterness outside, so its real work for me) hopefully Ill get to it this weekend.


kel