Stainless Steel Bushing

[Wongster]

Hi guys,

My dad, who is in the business of manufacturing syrups for flavored drinks, asks me to make for him several pieces of stainless steel bushings to replace those worn ones in a drink dispensing machine. I know that there are several types of SS and that's why I need your input on the right type to buy.

The bushing will be submerge in the drinks and therefore, need the type that will not contaminate the water.

May I know what type of SS should I buy?

Regards?
Wong

[Tony Wells]

Food contact stainless grades are normally T316 or T304. Both are NSF approved for piping systems involving beverages and food products. I would recommend T316 for anything with PH that is very far off neutral. It is far more corrosion resistant. Of course, sanitizing the system prior to use is still required. I have done a fair amount of design and manufacturing work on water purification systems, and have investigated the very issues you are concerned with. If you must weld any part of the system rather than use sanitary fittings, specify T316L or T304L.

[Wongster]

Tony,

Thanks. I don't get to find anything with the 'L' given the volume. I need to make 50 pieces, each about 20mm in length. I'll go for 304 since I know who will sell me.

Is it hard to machine?

Regards,
Wong

[Wongster]

I've made a sample piece using aluminium to pass over to my dad to test fit. While working on it, I realised that I'm unable to figure out the depth of the taper in a 5.5mm hole and it's angle from the sample given. I believe it to be either a 60 or 90 degree taper, but how can I confirm that? and, how To find out how deep I need to drill with the c/sink bit to match the sample?

The one on the left is the sample given to me, by a machine shop which is no longer interested in the business due to the smallish quantity of 50 pieces per order. The one on the right is the aluminium piece I did for test fitting.


The original piece that came with the machine on the right. It is badly worn from
The spinning magnet. I'll put in the 5mm diameter notch which the machine shop left out, but present on the original to keep the bushing from moving.


Is there a way to figure it out?

Regards,
Wong

[Bill Gruby]

I have machined 304/304L on occasion. It's not all that bad to machine. Here are it's mechanical properties.

http://www.upmet.com/products/stainless-...mechanical

"Billy G"

[stevec]

Wong, can you measure the depth of the sample bushing's countersink? A plug in the straight bore held just at the small end of the taper would give you the depth using a depth mic or digital caliper (if that level of precision is acceptable).

[easymike29]

(07-22-2012, 04:36 AM)Wongster Wrote: ....I realised that I'm unable to figure out the depth of the taper in a 5.5mm hole and it's angle from the sample given. I believe it to be either a 60 or 90 degree taper, but how can I confirm that?......Is there a way to figure it out?

Regards,
Wong

If you have a Vee block, sine plate and dial indicator it's relatively simple to measure and duplicate.

Gene

[Sunset Machine]

Or in a mill or lathe with a test indicator. Still half-asleep, but if you put the ball on the edge of the taper and feed it in until the DTI reads .015, the feed for 60 degrees would have been .008, and for 90 degrees, .015.

It's called "trig" and every machinist should learn the basics, especially right angle triangles. Simple stuff, really. Use the calculator on your computer in scientific mode.

Tan = O/A where O is opposite of the angle, A is adjacent to the angle. Where the two meet is 90 degrees.

The tangent of 45 degrees (half of 90) is 1.00 ... So... 1 x .015" = .015"
The tangent of 30 degrees (half of 60) is .577 ... So... .577 x .015" = .008"

If that's wrong, then it isn't as simple as I've indicated and I need more coffee.

I guess in this case it would be easier to use a lathe and the compound, and simply read the angle directly but that still doesn't let you off the hook for learning trig..

[Wongster]

Guys,

Thanks for responding.

The hole is about 5.7mm in diameter. I believe it to be done using a 5.5mm drill as the hole I did using a 5.5mm produced the same reading on the small hole gauge measures the same 5.7mm.

Steve, the depth gauge I have has a shallow hole (like a counterbore) that is just about the size of the surface where the countersunk hole is. So I couldn't sit the part on it properly to start. Further, I can see the plunger in the hole to do the measurement. The tail of the vernier roughly measures about 1.5 to 1.6mm in depth. I measure the length of the slope to be about 2.5mm using a piece of steel wire and the nail of my thumb to mark the distance. But I'm not sure I'm measuring right.

Gene, I do not have a sine plate. Didn't get one as it seems rather complex to use.

Sunset, I use GWizard that has a trig calculator. I'll try the DTI method you mentioned later.

Update: I dug out the angle gauge and use the 2 pieces marked with 30 degree and 45 degree. It fits the one with 30 degree better than 45. So I think it might just be 60 a degree countersink though the result I get doesn't really look like the same on the sample piece. Think it may be easier to measure the dimensions off the machine it is supposed to be used on. I'll try to make time.

Regards,
Wong

[easymike29]

Wong

As suggested by Sunset Machine you can duplicate the angle by chucking and truing the sample piece in your lathe. Then mount a dial test indicator somewhere on the compound so that the indicator point is contacting the angle at the 9 o'clock position as if it were the cutting tool. By tapping the compound one way or the other you'll eventually be able to achieve a 0,0 reading as you wind the compound in and out. Now you have the angle set even though you haven't measured it.
To accurately measure the depth of the angle you can compare your depth with the sample part depth by using something like a 644 jz Starrett depth indicator with an appropriate contact point. A point that contacts the angle anyplace within its extremities will suffice once the angle is duplicated.
To actually measure the angle is something you may want to do later. For now you can make your parts.


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