machining tapered hole?

[wagonist]

I need to make an adaptor to bolt an airflow meter onto an airbox from a different model.

The difference in size is 66mm dia hole in the airbox to 60mm diameter for the meter.
There is a small bellmouth arrangement with welded nuts used to bolt the original larger airflow meter to the airbox so I want to keep that,
then bolt the adaptor to the airbox,
then bolt the other airflow meter to the adaptor.

The outer shape & the bolt holes are no problem, but I'm curious about machining a tapered hole through the centre to smooth the airflow.

Attached is the adaptor.
Green is airbox, red is replacement airflow meter.

And before you ask, I can't just use (not without extremely difficult) the larger airflow meter because output voltage range is different (0-5V vs 0-10V)

[andrew_mx83]

silicone joiner & hose clamps?

[wagonist]

Unfortunately no room for that length.

That would also mean making a bolt on pipe to the airbox, another bolt on pipe for the airflow meter.

If it's going to be too hard, I'll get the hole made to the smaller one & hand file the taper, it'll only be 8mm alloy plate.

[andrew_mx83]

dremel FTW then if u dont have access to a lathe. filing would take forever!

[stidnam]

bolt piece to rotary table on mill bed and angle the mill head to desired angle. Rotate the rotary table and there you have your angled bevel.

[wagonist]

I haven't had any machining experience (I wish I'd done metalshop at school), so I didn't know if it was possible.

Now that I know it is, anyone got access to a lathe

[Sam_Q]

I could machine that taper for you if you want, whats the outside diameter?

[wombat]

What airflow meter would run upto 10 volts?
all electroinc devices and ECU talks to are only a max of 5 volts?

[wagonist]

There was deliberately no mention of make, model, or age

FYI: 89 Subaru Leone (Subaru only changed to hotwire from flap in 87, funnily enough the 89 Liberty/Legacy runs a 0-5V plastic hotwire meter).

[wilbo666]

If the stock AFM is 0-5V and the replacement is 0-10V then just setup a resistive voltage divider to make it 0-5V.

If the stock AFM is 0-10V, then use an op amp with a gain of 2 to scale the 0-5V AFM to 0-10V.


My suggestions

Cheers
Wilbo

[wagonist]

A bit of confusion.The stock AFM is 0-10V, the airbox being used suit the 0-5V version.
Not quite sure what signal the temp sensor is.
Just easier the way I'm doing it.

[Hen]

One method is to take a pipe as close to 66mm ID as possible, then cut a few (3-4) slits along it's length so you can crush the other end down to 60mm. The slits will need to be slightly triangular and the longer the better, it'll take a while to get right. Then TIG the slits closed and weld suitable flanges on each end.

If the welds get nasty inside you can always clean them up with a file/die grinder.

Hen

[allencr]

The difference in size is 66mm dia hole in the airbox to 60mm

Anyone with a lathe & 4 jaw chuck & compound rest can do it. Giving them a specific angle would make it easier then having to guess at it. Centering it will take the most time.
A die grinder or electric drill with a rotary cutter/burr will do a good enough job, just not as pretty.

[Cuts]

^^what he said, lathe with a 4 jaw would do it fine^^.