Making a brass funnel

Machine Shop
#1

I need to make a funnel out of Brass or some other material that doesn’t spark. I’m planning to do this on the Sherline lathe since it’s small, but I haven’t done much with brass before.

Any notes on types of brass or working it I should be aware of? I heard something about it hardening as its being worked, but have no indication as to why that would happen with any level of significance without torching it. I’ve done aluminum and steel but never had a need to work with brass before.

The other concern is if we have a cutting head available for the sherline that can make the inside mouth of the funnel. Not trying to make a super smooth curve or anything like that, but it would be a slanted profile after some flat inside walls.

#2

How large does your funnel need to be?

#3

Approximately an inch wide, and opening slightly smaller, down to .26" or so neck. Two inches long at the most.

Dimensions are flexible; I’m making this funnel for a specific application and the item being poured into is fairly small.

#4

Brass does work harden, but it does so mainly when being formed: pulled, bent, or compressed (e.g hammering). Cutting on a lathe doesn’t do much and it’s limited to work hardening right near the boundary where the cut is made and each subsequent removes the prior layer so it really doesn’t built up.
If you are worried buy it in H-0 or H-1 as it is softer. The most common form is H-2 (half hard), it machines nicely and less likely to gall when cut.

What is the wall thickness? The end piece of the funnel can remain solid until the lst step then bore it out. When doing the tapered sides when you get down below .125 wall thickness, go carefully. Not sure if it would be better to do final cuts from inside or outside to avoid distortion. Of one thing I’m sure you’ll want a new insert to do this so it is very sharp to minimize pressure applied.

Reminder, do not use lubricants unless they are specifically non-staining for brass.

If you can allow for a thick wall, say >.090" you’ll probably have you best results to avoid deformation.

If you’ve done it in Aluminum you can do it in brass - by the way Aluminum also work hardens. Stainless Steel is the nasty one for work hardening.

#5

Should clarify, that .26 is an inner diameter. I can make the walls as thick as I want since the funnel neck slips over the opening of the container.

I’ll see if I can get some stock from those alloys.

#6

Have you considered making it out of sheet instead of billet?

1 Like
#7

I have, but I want something a little sturdier for long term use and I don’t want spots like seams where the material could get caught. I would also have to fuse the sheet with entirely non-sparking materials etc. Using this funnel is a very repetitive process, and it’s going to get a lot of wear so I was planning on overbuilding it a bit to account for that.

2 Likes
#8

If it were me, I would make the spout end on the Colchester (since you said it could have a thick wall). That end will require a fair amount of stock removal which will go faster on the Colchester. And you can drill a larger hole there also. Then I would turn it around and make the cone on the Sherline by indexing the head.

#9

Thanks for the input. Yeah I was planning on the head index, but didn’t think about how long it might take from pure material time for the other end. I’m unfortunately waiting for another Colchester class :stuck_out_tongue:

-Jim

1 Like
#10

Funnel made successfully on the sherline this afternoon; took a little longer than planned, mostly due to the available cut faces.

Do we usually have any cutting points that don’t have as much material on the head? Biggest issue I encountered was when making the inside of the funnel the cutting head would bottom out against the shrinking walls.

1 Like
#11

photo please. Hopefully you took several showing the process. You are clearly qualified to teach the Sherline lathe … members awaiting seeing your first class on calendar!

2 Likes
#12

heh, if I find some time to sit in on another class first happy to teach some.

So the funnel slips around the mouth of the container, and facilitates pouring into the small opening. Since this is a slip funnel, rather than a traditional in-mouth design, it’s simpler to make. However, I am making some of these in different sizes so I’ll document the process a bit when I make the next one. I’m also going to start doing some profile cuts anyway to reduce weight and provide a bit of a stronger grip. I’m also trying to optimize the size, and will profile down such that the end for the container mouth tapers so it won’t bump up against adjacent containers.

IMG_20180625_032234
IMG_20180625_032234.jpg2138×2851 1.68 MB

IMG_20180624_191304
IMG_20180624_191304.jpg1200×1600 250 KB

1 Like
#13

I expected to see something very different - more like a traditional funnel with a tapered outside.

If this is the configuration what you need is a cutter that matches the angle on the inside. I would suspect that the angle isn’t even critical.

The easiest way I would do this is to use one of the large countersinks we have. In the cabinet behind the Bridgeport, middle shelf, left hand side, there are some gray drawers with cutters. I believe on the bottom drawer towards the left are some large countersinks/vee cutters. The largest ones have a hole through them at an angle.
image

First bore a hole all the way through the diameter of the through hole. Then use the large angle cutter to take it out full size. You can use Vee Blocks to hold it it vise on the Bridgeport. If doing on the lather you’ll a collet to hold the cutter - it can’t be held in a drill chuck without damaging.

Just go down until the hole at the top is as wide as you want, you can leave a band around like you have or even take it out to the edge.

2 Likes
#14

So the reason for the lathe is not for the funnel portion, but to match the contours of the container it goes on. I could order a set of bits for that, but I’d be looking at about $300 for the bit set to match the contour. The mouth of the funnel is a simple 50-degree and could be done with the usual 45 degree countersink. That container-side contour on the other hand is the tricky part.

The next ones are going to have quite a bit of material removed from the outside, as in testing it is shown to be too fat. This will require the outside taper, to prevent it from knocking against adjacent containers.

-Jim

2 Likes
#15

come to the Machine Shop Committee meeting and push for the CNC lathe to be fixed. This will solve your problem.

1 Like
#16

on my massive to-do list; even if the CNC portion were not finished, but the autodrive were available on a sherline that would be divine.

~H

#17

Last I remember @Chris_Wischkowsky was going to double check the list before we ordered the parts. The committee voted to NTE 800$ for that if I remember correctly.

#18

Awesome! I’m also really looking forward to the CNC lathe being up and running, I would definitely support it at the meeting but unfortunately I’ll be out of town

#19

Made a new version with less mass and works better when filling a bunch of tightly packed containers. I think this is closer to what everyone thought I was originally making

IMG_20180626_175316
IMG_20180626_175316.jpg2851×2138 2.9 MB

IMG_20180626_175905
IMG_20180626_175905.jpg2138×2851 1.6 MB

Edit. Decided to knurl the top of it because why not?

IMG_20180626_231850
IMG_20180626_231850.jpg2138×2851 1.65 MB

2 Likes