There's lots out there, but many look like one-time use throw away junk. Needs to be compatible with stainless steel and hardened steel. Uniburr bits aren't available anymore, at least that I can find. Any suggestions for a high quality alternative?

I would look on a good industrial supply site to identify what you are looking for first. Then do a search for that product based on price with shipping.
What are you looking to deburr? Holes, flat stock, etc.?
Also look on eBay for industrial surplus with a name brand or part number, it's right after a zillion Chicom cheap stuff ad's. Just put a minimum price in your search to bypass most of those.
Also look up Scotchbrite wheels that you used mounted on a bench grinder. They are great for lots of general purpose deburring and removing all sorts of sharp edges. Pricey but last a long time and save a lot of time. Like the other stuff, identify the product on the manufacturers site first, then do a price search for much better prices.

https://www.3m.com/3M/en_US/co...730+3294857497&rt=r3

I'm not sure what your trying to do or size but look at some carbide chamfer bits.
"MSC direct" has many different styles and sizes. More info needed for recommendations.

https://www.mscdirect.com/brow...ols&navid=4287924507

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https://www.freertool.com/tube...deburring-chamfering

Used smaller ones (Severance I think) at an auto supplier making brake and fuel lines. Mounted in a slower fixed drill motor. Larger tubes require something to grip the tube/pipe before pressing against the bit. Stainless will also need something to hold it.

I'm looking to chamfer and debur 1/4" + size screws with fine threads. I seem to be able to do it fine on a grinder on a 20 thread bolt. But on finer threads, like 28, it's hell for me to get that tip just right. What I've been doing is shortening the screw, then chamfering, the running it through a die to get the tip thread just right. I don't know. Maybe I need a finer grinding wheel. I never seem to be able to get the tip just right enough to easily start. I was thinking that a bit would leave a cleaner tip than the grinder.

quote:

chamfering/deburring bit

I'm completely confused on what you are looking for with the above description especially the bit part. You want to deburr the outside diameter of a cut bolt?

I don't have a tool recommendation but it can be a bit of a trick. Threading a nut on the bolt before you cut it will straighten the threads out when you run the nut back off though.

I think mark60 is on it... do you have enough length available on the screw to run the die down on it before you grind it off?

example...
https://www.fastenal.com/products/details/0894270

quote:

Originally posted by mark60:
I don't have a tool recommendation but it can be a bit of a trick. Threading a nut on the bolt before you cut it will straighten the threads out when you run the nut back off though.

I hadn't thought of that. I suppose I can get a 28 thread nut and try that.

I want to taper the tip a very tiny bit. I won't be using the screw with a nut, I'll be feeding it through a piece of aluminum into a piece of steel that has been drilled and tapped. So it's sort of a blind feed into the hole and I don't want to risk damaging the threads in the hole.

I don't really know how to explain what I have been doing. If I shorten the screw, a bur develops that keeps it from feeding into the hole. So I taper the tip of the screw to remove the bur, but I can't seem to get that bur off without tapering that screw more than I want. I need about 6 threads of the screw in the hole, no more, no less. I can't seem to get the screw right unless I end up knocking off the two end threads.

I am not sure a chamfering/deburring bit will really help me. I figured the cutting action would leave the tip bur-less, but I am thinking now that the taper might be too great and take off too many threads.

The nut solution may be the best solution so far. Again, I hadn't even thought of that.

quote:

Originally posted by hrcjon:
example...
https://www.fastenal.com/products/details/0894270

That's what I was thinking. It's not in stock and Uniburrs apparently aren't made anymore.

But I think I will try mark60's recommendation. It seems like a very simple solution.

Thanks for the help.

I sent you the link to the tool you need as an example. you can get one in lots of places as in its readily available on amazon (no idea of the quality of what's shown, but they are inexpensive). and no it doesn't remove threads. Having said that I have no idea of the volume we are discussing? In order of easy and finish why not just order the screws you need in the correct length? When I shorten fasteners (you say hardened, how hard?) I thread a die on the fastener, cut it, chamfer it on a bench grinder and then remove the die to clean up the threads. On a once in awhile basis a nut works, but more than a few times and that isn't the best. and sometimes if I'm lazy out in the boondocks and no big number of cuts I just use a hand file to clean up the end.

And chamfering with the die already on it seems like an even better idea. Never thought of that, either.

The screws are 1.25 inches. And I need screws that are 2-3 threads longer. All I can find are .25 inches longer. So I cut them and ground them the rest of the way.

I'm going to need 4 total, and would like to have a few more. That's all. So I've been practicing but haven't perfected it yet.

How hard? I have no idea. Just "hardened" carbon steel.

As for the bit, I thought it might be useful for other projects at some point. But after considering it, I think it might be too much of a taper and take off too many threads.

I'll try chamfering the screw with the die already on it. I had been putting the die on the chamfers screw, but moving it up to the tip after grinding seems like a better idea.

I think we are talking 1/4-28 x 1.25? If so I can find them in just about any length. for 4 an odd length would be expensive but Mcmaster Carr has then in .125 increments (about .070 over your limit) and is very easy to buy from. https://www.mcmaster.com/screw...ocket-head-screws-8/. I would think that would be close enough, but if not then either a small washer under the head could be a possibility;

quote:

Originally posted by hrcjon:
I thread a die on the fastener, cut it, chamfer it on a bench grinder and then remove the die to clean up the threads.

I just went out to my grinder and tried this on my practice screw and it worked perfectly. Gave the tip an extremely shallow taper and screwed the die off. Turned it through the resistance. It fed into the hole perfectly.

Thanks for that. It's a simple solution.

Just saw your latest post. I'm not sure what 2 or 3 threads equates to, but it's easy enough to shorten the longer screws I've got. I really wanted learn to do this myself. Now I know. Thanks for the advice. And to mark60 as well.

A good set of thread files is also a good thing to have in your toolbox. They are hardened and are about 1/2" square with four different thread pitches on each tool. I have them in inch and metric sizes. Work wonders for fixing or debuting threads especially if you can spin the piece your trying to fix, Shoo

quote:

Originally posted by Micropterus:

quote:

Originally posted by hrcjon:
I thread a die on the fastener, cut it, chamfer it on a bench grinder and then remove the die to clean up the threads.

I just went out to my grinder and tried this on my practice screw and it worked perfectly. Gave the tip an extremely shallow taper and screwed the die off. Turned it through the resistance. It fed into the hole perfectly.

Thanks for that. It's a simple solution.

Just saw your latest post. I'm not sure what 2 or 3 threads equates to, but it's easy enough to shorten the longer screws I've got. I really wanted learn to do this myself. Now I know. Thanks for the advice. And to mark60 as well.

This is a great idea and would be my recommendation as well if you have the die. Before I saw it, I would have recommended threading on a nut, or two if there was room, cleaning up the burr on grinder with fine wheel, or, even with a file by hand, then threading the nut/nuts off. I've done it many times with coarser threads, a few times with fine threads. Just have to be more careful and meticulous; same procedure.

Uniburr is a conicol deburring tool that will help by leaving a good angle after taking the first couple of threads back.

(used to work in a machine shop that used a similar device on the "screw machine". It took screw and bolt "slugs" cut threads, then stabbed in the cone, deburred and tapered the end. It was fast.)

A lot of good info has been offered here. With your patience I will reiterate. FIRST - for hardened materials you MUST have a bit harder than the parent material. This means you will almost certainly be looking for a carbide chamfering bit. Now one mistake that beginners make is that they want to chamfer the threaded hole AFTER it has been tapped. This will ALWAYS add a couple of steps to the operation and will usually yield a less-than-satisfactory result. You MUST always chamfer the hole BEFORE you thread it. IF you do this you will have no problems starting the bolt in the threaded hole. Any number of machinists or retired machinists on this site will- I am sure -be willing to verify what I have said...... FredT

 
When I cut off a screw (small or large), I take it right to the 1" belt sander (80 grit belt), smooth the end, and then at ~45 degree angle make one 360 turn on the end for the chamfer. I've never had to use a die or nut to clean up the threads, the screw goes right in. If necessary (small and/or short screws) I hold the head in a pair of soft grip pliers. I've done hundreds that way. I typically buy my screws from McMaster-Carr in the longest fully threaded length they offer, then cut them off as needed for each job. Hardened or stainless screws pose no problem with this method.