I am very new to operating a bridgeport and this is my first attempt to install the first R8 tool I received from CDCO.

The bp was purchased with a threaded rod that has a bushing that can be removed when the first part of the threads get mashed I was told.

There may be two problems.

1. the threads on the rod and the tool do not match. I do not know what the correct thread is supose to be, isn't all r8 tooling the same thread size?
How much thread is supose to go into the tool, I have watched tooling being installed and it looks like the htreads should just be very loose all the way until you use a wrench to tighten the taper.

2. I may be an idiot

Please advise.

Pictures of problem.

http://www.siliconcoder.com/r8tooling.html

Working with PDA so I did not look.

Is your threaded rod the correct part or all-thread?

Correct part will wor correctly and stripping threads not issue unless you are the type that eats a lot of bananas and walk on your knuckles...

Well that is the question, the rod has no markings, I did not buy it, well I guess I did as it came with the machine but I don't know where the guy bought it.

So I guess I really don't know if R8 tooling has different thread sizes at the moment as niether the threaded rod or the tooling says it is metric or standard just R8 and I thought that is all one needed to know. I don't see any thread sizes mentioned in any of the tooling advertised so I assumed the rod was correct.

Kind of like plumbing a sink for the first time, how many different size fittings do you suppose there are under the sink, I can tell you, too many.

Something is not right. It should thread freely until it snugs up. Do you have a tap and die set in this size to test the threads? I believe mine is 7/16 NC thread.

Nope, that is why I am a bit frustrated at the moment, i don't have any thread measuring tools or even a box of bolts.

I see it looks like the thread is 7/16 - 20


If that is correct then the guy that sold me the press just bought the wrong one unless there are different threads on all of the R8 tools but that would be a nightmare I would think.

I will order a new one, I am pretty sure the one I have must be metric.

Perhaps someone has a link to a drawbar not made in china? I don't like buying crap from china but I don't know where to buy American made drawbars.

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All of the R8 collets and holders that I have use a 7/16-20 thread. Just check your drawbar with a thread gauge and see what you have. You probably need a new drawbar to match.


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Look Tony, they guy I bought this bp from has 40 hp CNC machines and has been in the business for a long time. I assumed he would have given me the correct drawbar, so I did not get out the big hammer and the mega wrench to make it fit. I ate the last bananna we had yesterday and I have not bought any more.

It might be worth going to the hardware store and buying a 7/16 20 die and rethreading the drawbar. It would probably be cheaper and then you would have a die. Believe me if you are getting into machining you will want a tap and die set.

I wonder if some Chinese (CDCO?) R8 tooling has metric drawbar threads. I would start out trying to buy a 7/16-20 nut and bolt. Try the nut on your drawbar and try the bolt in your R8 tool. Cheap gages, and maybe you can just take your tool to the hardware and try the bolt without buying it.

Larry

The R-8 collet is defined as having a 7/16"-20 thread. Here's a drawing from a Bridgeport brochure:



I've heard that there are some collets/drawbars with metric threads, although I've never seen any. It's possible you've found one or the other.

You can buy accessories from most industrial supply houses, such as
MSC at www.mscdirect.com
McMaster-Carr at www.mcmaster.com
Reid Supply at www.reidsupplyl.com
and of course on ebay.

The breakaway drawbar you described is a standard item, available from those suppliers.

- Leigh

I had a very similar problem with a drill chuck with an integral R8 shank from CDCO.

The actual problem had nothing to do with the threads but with the actual diameter of the R8 rear shank. It was a tad bit to large for the bore inside the spindle so it would not seat into the taper. What I ended up doing is mounting the chuck up in a lathe and machining a few thousands of the end. Fit perfectly after that.

Now I might be completely wrong in your case, but if you remove the draw bar you should be able to completely slide the tool up into the spindle (full engagement of the taper). If it does not you have the same problem I had. If it truly is the threads make sure the thread on the top of your R8 tool was not tapped on an angle (cheap import ).

No. I've purchased collets and end mill holders from CDCO. They are inch threads. If he were selling them in metric, this would be noted.

Your suggestioin here is a good one. Take the collet and the drawbar to the hardware store and try some nuts and bolts. I did that many times for metric sizes when I was refurbishing my Webb Mill earlier this year. I finally learned what the metric sozes look like, too. LOL.

It sounds like the drawbar has a bad thread or is actually metric for some reason. It's possible that some R8 units for Europe are metric but I woldn't know about that.

Good luck.

It is a bad thread on the drawbar, threads fine up to 7/16 of the way in then gets stuck where the threads come to the break point.

I have a tap and die set at my printing business, (my bp is at my home), I will just finish the threads through that breakpoint.

One other thing I see they have drawbars for 1J and 2J heads 21 and 23 1/4 here

http://www.nolansupply.com/bysubcate...lse&specs=True

My head says J124154 so when I do order another one I think I will guess J1 at 21"

I am shure rethreading this bar will work now, since I don't work with threads much I just initially thought if it is the same size but dosen't fit maybe it's metric.

J1 is a step pulley head (manual belt change), the 2J is a variable speed head (hand wheel).

Glad to hear you got the draw bar working.

Glad you posted as well, same reason I don't gamble at the casino, I guess my head is a J2 head because it is variable speed with the handwheel. I bet if I put all the extra plumbing fittings I have on ebay I could buy myself a very nice face mill or even kurt vice.

I would run a 7/16-20 tap into the R-8 tooling,there could be crap in the threads,then run a die over the drawbar.

I just got here,,,but that is exactly what I was gonna say!
cdco's stuff is ok for the price you pay I guess, but a lot of time you have to finish manufacturing the tools.

I've not had any problems with CDCO tools fitting. There were a some poor quality set screws on a few of the BXA tool holders but every thing else has been very good. I just bought a box of metric set screws from McMaster-Carr and haven't needed any on later toolholders from CDCO.

The OP had a difficulty with his existing drawbar, not the tool.

Additionally...

Make sure the spacer/washer is on the drawbar right under the head.

These are usually thick (approx 5/16 or 3/8...can't remember) and some; but not all are held in place with an o'ring.

This might be what you were referring to when you said "....with a threaded rod that has a bushing that can be removed when the first part of the threads get mashed I was told."

Don't leave this part off.... it can be shortened to accomodate the buggered threads, but I've never seen the need to do so.

Also,

When you remove the drawbar and slide the collet or tool into the spindle, it should move freely until the taper seats.
If not, check to make sure the small flatted set-screw inside is not causing a bind.


This topic was discussed previously.

Even a different brand of tooling can have too shallow a keyway, which may bind up, and it acts just like what you're describing.

Another thing to check.....new tooling can sometimes have serious burrs along the keyway on the side that engages the flatted set-screw. Same scenario... Stone them off.

Sounds like you're right Gatz. If it threads up to the renew groove you definitely need a bushing under the drawbar head. When the first thread section wears out, you saw it off and discard the bushing.

Ray