Press Fit

[DCP]

I dont know anything about press fit.

I want to press fit a .120 steel pin in Aluminium. Is steel to steel any differant?

What size do I make the hole?

I have a Arbor press.

What else dont I know.

Thanks

[elk hunter]

I generally use .001 as the difference when pressing in parts one inch or smaller in steel, I would think it should work with aluminum. Remember a drill will generally make an over size hole. It is best to drill and then ream to diameter for an accurate hole. If the hole has to be very straight you should drill, lathe bore and then ream.

Hope this helps.

[Reg]

Press fit is not only relative to material but also to diameter.
In your case .0005/.0004 would work ( aluminum is abrasive and actually requires less PF than steel ) .
Drill 1/64 undersize and finish with a reamer.
.001 might work as well but depending on form, could cause distortion.

:bigsmyl2:

[Whiterabbit]

We do that at work (press fit a steel pin to an aluminum machine part with an arbor press, and that thing is PERMANENT.) I can ask about the hole dimensions if you like.

Talked to our guy (surprised he came in this early), our pin is .250 and the hole is .249. He said we could probably have done .2495, but .249 works for us.

[DCP]

Any help is appreciated

I only have to make 1 part so I dont think buying a reamer is option

So I could drill a .125 with a 1/8 drill
Then measure the hole
Turn the rod to the right size
use the arbor press

The pin is going to be in a 1/4 wide 3/4 dia round disk

Turn,file or use some emery paper the 1/2 long pin to .120 dia

or just JB weld it

[paul h]

An 1/8" drill is not going to drill a 0.125" hole, nor will it be truly round. Press fitting is a precision operation and you really do need to ream the hole. As I recall from my shop days the difference in dia for a press fit is 0.001" per inch of dia, so for an 1/8" hole you'd want 0.000125". but not really an option to hold such tight tollerances, so 1/2 though will provide the grip you need without too much distortion. There are also some dodges for when the hole ends up too big, or the pin too small. You can knurl the pin to increase it's dia, or you can dimple the hole with a punch to raise it's surface. There is also loctite.

I'm not quite picturing what you want to do, but would a viable option be to drill an 1/8" hole through the plate, an 1/8" hole through the 1/4" wide 3/4" dia disc and use a roll pin to hold them together?

http://www.micromatic.com/images/3/300x300/100-302.jpg

[DCP]

Go to the pics of Mags
I may want to make a guide rod also


http://www.thetruthaboutguns.com/2012/03/joe-grine/tricking-out-your-gsg-1911-22/

[deltaenterprizes]

It looks like they used a roll pin

[Longwood]

You have entered the realm of the number drills.
Buy a set.. They are not in order like fraction or metric drills. They are made in special sizes for exactly what you are attempting.
They come in really handy for what we tinker with.
You will use them many times once you have them.
I have used them to make tiny hinges by drilling holes the proper sizes then cutting a drill shank for a press in pin.
If the pin you want to use is soft enough, you can use it in a too big hole, by making it into a "Drive" pin. I lay them into vice jaws set narrow then use a small punch or better yet a cold chisel too upset enough of the pin to hold it in a hole.

[seagiant]

Hi,
I don't really know what your doing but one option I use alot even though I have a 30T shop press is to do just a tight slide fit and then use red loctite? As long as you are not using it in a real hot temp situation and prep right it's not going anywhere!

[JIMinPHX]

If you are pressing a dowel pin, then you need a reamed hole to be accurate enough. Dowel pin reamers come in standard sizes for standard size dowel pins like 1/8", 3/16", 5mm, etc.

If you want to press a pin into a drilled hole, then you need to use a roll pin or a spiral pin. They are made to work in the looser tolerance of a drilled hole. You can use a 1/4" drill for a 1/4" roll pin.

If I knew what you were doing, I might be able to give more in depth advice.

[DCP]

Try this





If you are pressing a dowel pin, then you need a reamed hole to be accurate enough. Dowel pin reamers come in standard sizes for standard size dowel pins like 1/8", 3/16", 5mm, etc.

If you want to press a pin into a drilled hole, then you need to use a roll pin or a spiral pin. They are made to work in the looser tolerance of a drilled hole. You can use a 1/4" drill for a 1/4" roll pin.

If I knew what you were doing, I might be able to give more in depth advice.

[John Taylor]

Looks like an easy part to make. I would add knurling for added grip. If the pin size must be .120" the you can use a reamer that is .1195" available from http://www.mcmaster.com/#reamers/=ivg4f9, Price $15.18 plus shipping.
In this type of application a 3/32 ( .093") roll pin would most likely work fine. They are made of spring steel and would be plenty strong enough to do the job. Use a standard 3/32 drill and the pin can be found at most hardware stores for probably less than $.50

[DCP]

This is what I have decided to to.
Called the hardware store ysterday 3/32 roll pins are $.10



Looks like an easy part to make. I would add knurling for added grip.
In this type of application a 3/32 ( .093") roll pin would most likely work fine. They are made of spring steel and would be plenty strong enough to do the job. Use a standard 3/32 drill and the pin can be found at most hardware stores for probably less than $.50

[Casting Timmy]

Press fits are a tricky situation, if you;re using a bushing and the press fit is too great you will change the inside diameter of the bushing. When I design for a press fit at work with metal a size on size fit will give you a press fit, typically people shoot for a half thousandths press fit though.

If you over drill the hole, there are a few tricks you can use to get the press fit back. You can glue it in, you can also use a ball bearing place on top of the hole and hit it with the hammer. You can also stake and deform the hole after the dowel pin is in place from the top or side of the piece if the dowel is close to the edge.

A roll pin would be your best bet for the magazine loader you;re trying to make.

[Longwood]

This is what I have decided to to.
Called the hardware store ysterday 3/32 roll pins are $.10

If you have a vice,, put the parts in it straight then close it a bit to press in the pin.

[TCLouis]

Looking at the part to made suddenly gives us all a hint that precision and specific sizes are far less important than what machinists consider important.

Perfect reason to have the project and purpose listed first and then the design and degree of precision can bedetermined

[Longwood]

Looking at the part to made suddenly gives us all a hint that precision and specific sizes are far less important than what machinists consider important.

Perfect reason to have the project and purpose listed first and then the design and degree of precision can bedetermined

Right,,,,

Drill a hole and push in a roll pin.

[DCP]

I got it finished last night

Pictures to follow ASAP


Thanks to all

[DCP]

3/32 3/4 in roll pin

I formed the pin face with a file

Thanks to all

[Longwood]

3/32 3/4 in roll pin

I formed the pin face with a file

Thanks to all

EXCELLENT!

Look at a lot of this very expensive stuff we need or want.
Much of it is so simple a person with few skills can often make it.
Watch out though,,,, the satisfaction from making it yourself can become enjoyable and nearly addicting..