Need advice on a problem...

[Jumpmaster]

So I was able to buy a book press really cheap...but I found it has a small problem.

The problem is the threads in the casting are worn out on one side, so one bolt (out of two) that holds onto the press plate is loose.

It can raise with only the one bolt that's holding it, but I'd like to go ahead and fix the stripped out side.

Would it be better to bore it out and try to press in a new threaded insert? Or tap it to a larger size and just get a larger bolt for that side?

Thanks for any ideas on this...

 

[Mmassey338]

What size bolts? What kind of metal is the female thread?

 

[will]

I have made up a number of booklets for some of my camera equipment. These range in size from 25 pages to over 150. I use 2 metal rulers that I clamp on the bound edge to squeeze them together, I just spread wood glue on the this edge. I then make a cover and back page that I fold around the booklet. I will use a utility knife to trim the other sides.

But, back to your question. I would not use anything that you just press in, unless it has a flange on the reverse side. This would prevent it from being pulled out when you tighten the screw, You could use one of those heli - coil, These are threaded inserts that screw into the 'body' an can retain the original bolt size. Lastly, you could drill it out and use a larger screw. A larger screw might be a problem on the top portion of the press.

( or - you could drill out the damaged thread to clear the bolt. Just put a nut and a washer on the reverse side. Easy and inexpensive fix. )

 

[precisionworks]

Heli-Coil. Be sure to buy the set that includes both the inserts + the special SPI tap. Be as good as new when you finish.

 

[Jumpmaster]

It occurs to me that a picture would help here...I will take some pics and post them soon.

As far as the material, I think it is cast iron...

Thanks for everyone's thoughts so far...oh, btw -- this isn't going to be used to press book bindings...I got it to press leather parts together after gluing to create a tight bond prior to saddle-stitching.

 

[precisionworks]

http://www.helicoil.in/helicoil.htm

 

[Jumpmaster]

Here are some pics for the curious...(There is no access to the bottom of the hole in question...the plate is solid and flat beneath the hole...)

Looks like the Helicoil may be the answer...

 

[precisionworks]

Those look like pretty small bolts ... Do you know what diameter or thread pitch?

 

[Jumpmaster]

That's my fault...I didn't really put anything in the pic for scale.

I haven't measured them yet, but I'd estimate the holes are approximately 5/16" diamater...maybe a touch bigger...

 

[gadget_lover]

That does appear to be cast, so welding, drilling and tapping is out.

You aren't trying to preserve the original look or feel, right? That being the case the easiest fix is to drill/tap for the next size thread. If you are concerned with looks you might want to do both sides so that they are matched. You might get lucky and find a metric thread that is the same minor diameter as the stripped out hole. That would leave you with only cleaning up the hole and tapping it, but not enlarging it.


Daniel

 

[Jumpmaster]

Thanks for your thoughts, Daniel...

What do you think about the Helicoil solution Will and PrecisionWorks suggested? Sounds like a good, permanent fix...would it be easier than drilling out and tapping a larger hole?

You are correct that I'm not concerned about keeping it original...I'd rather have it fixed up as best I can as it is going to be used frequently.

Thanks again everyone...

 

[will]

It took me a few minutes to figure out what I was looking at. The only pressure on the plate is downward, lifting the plate is minimal. The best fix would be the heli coils. I don't know the cost, second to that could be if a bottom tap is needed to get to the bottom of the blind hole.

You could get by just using a 2 part epoxy like JB Weld or even Devcon 2 ton to permanently attach the stripped screw

 

[gadget_lover]

Correct me if I'm wrong, but aren't the bolts there to retain the collar that is attached to the end of the big acme screw? It looks like the stripped thread is the one on the upper side of the second picture. Right?

A helicoil will not necessarily be stronger than drilling and tapping. Here's why. A helicoil is an insert that is threaded inside and out. Using a helicoil calls for drilling a bigger hole, then tapping that hole for the outside threads of the helicoil, then screwing the helicoil in. Only then can you screw in the bolt. In essence you have to drill and tap a hole that is several thread sizes larger than the original. A helicoil for a stripped 1/4-20 screw will require that you drill a 17/64 hole and then tap that.

A helicoil is appropriate if you have a need to still use a screw that is the original size. In your case there does not seem to be that requirement, so just going to a larger bolt will fix the problem with $20 less cost and 1 fewer step.

Daniel

 

[Jumpmaster]

Ok, well that all makes sense...thanks for the explanation on that.

The way the press is designed, that collar you see is actually in two pieces. The screws hold the collar in place and keep its pieces from trying to rotate while raising and lowering the press plate.

The big acme screw has just a ball socket end and turns inside the casting, under the two-piece collar.

Looks like I'll be looking for some taps and drill bits...this is a good reason (excuse ) to buy a drill press, right? hehe

 

[precisionworks]

A Heli-coil correctly installed is stronger than the original thread in cast-iron. Moglice is another excellent option: http://www.moglice.com/

 

[will]

to buy a drill press, right? hehe

I bought a floor drill press years ago. I really does come in handy for lots of different jobs. The one I have uses a belt system to change the speeds, I would suggest one that has a dial or variable speed motor to change the speeds.

Also, when you start to use the press, put some grease on the big screw and in the cavity where the screw 'attaches' to the plate.

 

[Jumpmaster]

Ok, will do...will white lithium grease work ok for this?

I think I may have it powder-coated...it looks pretty pathetic as it is now...

 

[will]

Ok, will do...will white lithium grease work ok for this?

Lithium grease is fine...

 

[gadget_lover]

A Heli-coil correctly installed is stronger than the original thread in cast-iron. Moglice is another excellent option: http://www.moglice.com/

Not to get off topic ...
I don't understand why it would be stronger in a case where the bolt should be permanently installed? You have two surfaces that interface with a helicoil. Can you explain why it's stronger?

Daniel

 

[will]

I am going to guess on this - I don't know about stronger, but the heli coil will stand up better to multiple times a bolt is threaded in and out. Cast will wear out quicker than the insert. precisonworks can probably answer this better than I can.

If this is going to be powder coated, make sure it gets a good clean sandblast to start, make sure all the threaded areas are masked off. Powder is thicker than regular paint. I have done a lot of powder of small items - flashlights - limited to the size of a toaster over that I use to bake the finish.