# make a jig for cutting 1/4"ridges inside pvc pipe



## wilfor03 (Jan 1, 2015)

Just want to throw out a request for ideas on a problem I'm having......I want to make a jig for cutting 1/4"ridges inside pvc pipe for making a reverse helix trommel barrel out of 8"PVC pipe for my wild hobby of gold prospecting? I know what my end result should be, but can't "see" how to do it in my head to build a jig for it? Any thoughts out there........

Bill :smile:


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## Herb Stoops (Aug 28, 2012)

wilfor03 said:


> Just want to throw out a request for ideas on a problem I'm having......I want to make a jig for cutting 1/4"ridges inside pvc pipe for making a reverse helix trommel barrel out of 8"PVC pipe for my wild hobby of gold prospecting? I know what my end result should be, but can't "see" how to do it in my head to build a jig for it? Any thoughts out there........
> 
> Bill :smile:


Bill do you have a picture of what you are trying to do, or is his an original idea?
Herb

i.e. you can coppy a picture you already have on your computer to this forum,they tell me.


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## Stick486 (Jan 4, 2013)

need more to form ideas...


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## DesertRatTom (Jul 3, 2012)

Just from watching Gold Rush on TV, I think you are talking about bars the are straight down the pipe, is that correct? If so, and if the pipe isn't too long, you might be better off attaching strips to the inside walls of the PVC. 

You must be using something like the thick wall pipe used for smaller mains.

If you made the strips of plastic, you could lightly afix the strip to a piece of wood, apply the epoxy or glue, run the wood strip into the pipe with glue applied just before inserting it. Then flip the wood carrier over so the glue contacts the walls. Personally, I can't see this lasting very long.

The trommels on Gold runs have water sprays near the top of and running the length of the trommel. The water washes the gold and smaller gravel off the larger stones and gravel. This means there needs to be some sort of grill so the gold washes out of the trommel into the rocker where water flows and the gold settles into riffles or a mat. The picture shows the trommel as a metal, heavily perforated tube. So I'm not sure you can make a PVC tube do this. If I were doing this, I'd find some flat stock with openings in it, install the bars while it's flat, then have someone weld the thing into a tube. I think that would hold up for some time with moderate usage.

Looks to me like the trommel has to have open ends for rock going in one end and out the other, and wash water going in the tube at one end.

Looking at the picture below, I notice that the separated gold and smaller particles drop down to a box that flows the opposite direction, then dumps the paydirt onto the end of the rocker. 

If you were going to do this with a PVC pipe, you could put in the bars, the drill a LOT of holes between the bars.

One last thought about the bars. Use some steel L bars, pre drill 3-5 5/16th holes to bolt it in place in the tube (Drill the center holes through the PVC from the outside of the tube), then drill the holes near the end where you can reach more easily. I'd use stainless bolts. Use a washer on the outside to reduce stress on the pvc tube. 

I assume you will be running a generator and water pump, or prospecting where you have sufficient gravity flow. I'll be curious about how you rotate the trammel tube.


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## JOAT (Apr 9, 2010)

Years ago I had a ton of info on placer mining. Making, and using, all sorts of gold machines. Worked with a young LT in Nam whose family panned on a big scale every summer. They used a dozer to push dirt into a large sluice box. Basically the K.I.S.S. principle, and it worked, they spent minimum time working on repairs. 

Do a google search for reverse helix trommel barrel. You'll get tons of info on making, using, buying. Me I'd make one, if I wanted one. But from what I've read and all, think I'd pass on one.


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## wilfor03 (Jan 1, 2015)

my pvc pipe is 8" od wide, 1/2" thick......just wanna cut a continuous 1/4" groove, 1/4" wide, spaced about 1-2" apart, the length of the pipe (about 3' long). There's a company out in California that would do it for about $300-$400. not counting shipping........too much money for that cuz its too much fun to try and make my own. That way if I mess it up/break it I'll know how to fix it, eh? I'm trying to attach a picture so this don't sound so silly, and I really appreciate all the help you all are giving me.....

Bill


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## 4DThinker (Feb 16, 2014)

Approach step by step...

What can cut a 1/4" grove? Small trim router? Check to be sure. End mill or ball-end bit perhaps?
What mechanical action can move the router forward (or the pipe backward) as it rotates inside the pipe (or the pipe rotates around it)? It could wind up a cable as it twists, and as the cable gets shorter it pulls the router up the pipe. Size winding mech so each rotation pulls the router your 1"-2". Once a few threads are cut a pin could be dropped in so the router just advances up it's own thread. 

Consider dust collection while cutting. Drag a vac hose up as the router climbs up the pipe. 

Only ideas here. Expand on as necessary.

4D


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## Cherryville Chuck (Sep 28, 2010)

If you are going length ways then one of the easiest ways to do it would be to split the pipe in half, cut the grooves, then solvent weld the two halves back together. The base of a trim router should fit far enough down into the trough to be able to cut that.


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## Nickp (Dec 4, 2012)

Cherryville Chuck said:


> If you are going length ways then one of the easiest ways to do it would be to split the pipe in half, cut the grooves, then solvent weld the two halves back together. The base of a trim router should fit far enough down into the trough to be able to cut that.


Very +1...


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## Nickp (Dec 4, 2012)

How about this...put a slice down the pipe...heat it until it can be opened and flattened...put it in a "press" for a while...route grooves with an edge guide such that the end of one matches up to the beginning of the other side...heat again into a circle...glue back together... VIOLA...

Welcome to the forum...


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## jd99 (Jun 17, 2009)

Find someone with a long metal lathe. 

put a form tool in a boring bar, and cut grooves


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## Blinky (Jan 25, 2015)

For a start, how about a dremel right angle attachment. If someone knows of an easy way to make an acme thread that would move the tool 1" per revolution.


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## wilfor03 (Jan 1, 2015)

Think after all the suggestions that I will try to use my Dremel tool if it will fit inside the 8" pipe with a 1/4" end bit (if the dremel has enough power) and see how that goes. I'll try and draw a reference line on the inside from the bottom up as a starting guide and once I have one full turn routed I'll see about making a guide jig for the dremel to set in with a 1" off set from the original 1/4" groove and go from there. I'll have to wait about 3 more weeks because I just had rotator cuff surgery on the shoulder and need to let that heal a bit more before I start playing. I can still start to get things together though for when I can start. I'll try to take pictures of the progress as I go and share them on here for those who may have an interest.........

Again, I thank everyone who has participated in this discussion and wish me luck, eh?

Till later on......

Bill


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## Blinky (Jan 25, 2015)

Had the same surgery 5 years ago on my right shoulder when I was 64. My therapist said to do the exercises they prescribed even if it was uncomfortable, but not till it was painful. Went to therapy three days a week at first, bought some of the same equipment, rope & pulley, rubber bands, etc. and did all the exercises at least 4 times a day. 30 days later I had full range of motion back, no more pain, and my surgeon said he couldn't believe I recovered that fast. I'd lived with that pain for several years and don't regret getting it fixed. Best of luck and hope your back in the shop soon.


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## TwoSkies57 (Feb 23, 2009)

could you cut 1" rings and just insert em and glue em up?


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## wilfor03 (Jan 1, 2015)

TwoSkies57 said:


> could you cut 1" rings and just insert em and glue em up?


Did that with the one I built already......it's hard to seat the cut/glued rings inside without leaving a small gap sometimes. 
And, since I am chasing mostly fine, flour gold, every speck captured counts, eh?

Here's a picture of the one I'm using now that I made with a single continous cut and glued inside the pipe.


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## Cherryville Chuck (Sep 28, 2010)

All the trommels I've seen are on a slight incline which means any grooves or coil at the top of the pipe aren't doing anything. In fact the pipe shouldn't be that full or the flow might be too fast for the gold to drop out. So why not just use a half pipe which would make it much easier to do what you need?


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## Old_Red (Jun 4, 2017)

If you can find a treaded shaft and nut with a 1, 1/2, or 1/4 tread per inch pitch a bit longer than the PVC pipe you need the grooves in you can make a plug that is a tight slip fit inside your PVC pipe with a hole down the center and a steel bar across the end of the plug. The nut that fits the shaft is very tightly fixed over a hole in the steel bar that runs through the center of the PVC pipe. 

Grind one or two lathe bits the shape you want the groove to be and attach them to the ends of the steel bar so the barely cut the PVC pipe and use a tube with a steering wheel to turn the plug in the pipe along with the lathe bits around the treaded shaft to cut the spiral grooves on the inside of the PVC pipe. If you have a 1/4 tread per inch treaded rod and want groove 2 inches apart put on 2 bits. If you want the 4 inches apart only use one tool. If you find a 1/2 inch per inch and you want 1 inch grooves use 2 tools.

Some oil or water will lubricate the cutting tool an make the cutting easier and cleaner. Once you have make one pass take the plug off the far end and bring it back and put it on the other end or spin the wheel backwards move the tool or tools in and repeat until your done.

If you can't find a treaded shaft and nut an accommodating fiend with a lathe to cut the treads on a shaft and make a nut might work. If you take to a machine shop it will probably cost as much as buying the pipe in California having him do it and shipping it to you. The advantage to have the tool made is when it come to making the next one.

Red


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## Old_Red (Jun 4, 2017)

I should have read all the posts first. Instead of making a lathe tool use the router bracket for a Dremel tool to attach to the wooden plug the screw pulls through the pipe.

I fixated on my first solution.

Red


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## wilfor03 (Jan 1, 2015)

Red.......
thanks for the reply and info, but I can't seem to "see" this in my brain as to what you are talking about.......could you draw a picture of the way you're trying to explain to me? I'm old and getting denser (sp) I guess, but thank you Red......I'll be waitin for the drawings....

Bill


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