Gunsmithing: Machining a dovetail

[tmkr]

The level is more than satisfactory for what needs to happen for that cut. Indicating it in would take more time than necessary.

If your doing a one off job,like gunsmithing,your indicator is your best friend.you get 1 chance to get the job right or it is forever #$%&ed up.nice job on the dovetail

 

[IndyGunworks]

If your doing a one off job,like gunsmithing,your indicator is your best friend.you get 1 chance to get the job right or it is forever #$%&ed up.

Hundreds of gunsmiths use a level for a dovetail. alot of other things i would most definatly indicate in though.

 

[GSPBirdDog]

No its an american made wells index from 1956. Still in as close to new condition as an mill that old comes. Less than .020 backlash in all travel. original scraping still visible throughout. Needs some table locking bolts, and an oil gun w/ a zirk fitting for way oil. right now i just sqirt it on the ways.

3 axis magnetic scale DRO gets delivered tomorrow for it

If you have .020 backlash then you have a problem....How are you checking for backlash?

 

[tmkr]

The level is more than satisfactory for what needs to happen for that cut. Indicating it in would take more time than necessary.

Hundreds of gunsmiths use a level for a dovetail. alot of other things i would most definatly indicate in though.

this is a good example of the old saying,take the same job to 3 different shops ,they will do it 3 different ways ,all of them producing a good part.

I would indicate it though

 

[IndyGunworks]

If you have .020 backlash then you have a problem....How are you checking for backlash?

I disagree. ALL machines have backlash of some sort or another. I could probably get my backlash to less than .010 by tightening up the gibs, but thats better suited for when i have the time to take it apart.

If you always approch a location from one direction then you never have to worry about backlash. I always zero my dials and write down the previos adjustment so i can always return to a previous spot. to return to a spot you simply go past it more than whatever amount of backlash the machine has then reapproach the proper location.

ALL machines have backlash period. at least these kind of machines. My understanding is that backlash can only be eliminated w/ ball screws which are not very typical on affordable machinery. I am checking backlash by putting a travel indicator on the machine but against the vise then moving the handle until the needle JUST moves, then counting how many thousands on the dial until the dial begins to move back the other direction.

once i get my DRO installed i wont have to worry about how i approach a measurement though, or even deal w/ backlash because the DRO doesnt care about backlash as it ONLY measures the movement of the table/knee.

brand new jets have around .050 thou of backlash right from the factory. these old indexs and bridgeports have at least a few thousands of backlash when they are new also. its a screw and its imposible to have ZERO backlash and still allow for movement.

 

[bluewraith]

once i get my DRO installed i wont have to worry about how i approach a measurement though, or even deal w/ backlash because the DRO doesnt care about backlash as it ONLY measures the movement of the table/knee.

Something to keep in mind.. your table can move a slight amount if you have not taken up the backlash in one direction or another. If you overshoot your number, and back off a hair to it you may be leaving the screw loose. Locking the axis will help, but you may notice your position will change even more when the screw is loose.

 

[IndyGunworks]

If you overshoot your number, and back off a hair to it you may be leaving the screw loose..

you mean like this

to return to a spot you simply go past it more than whatever amount of backlash the machine has then reapproach the proper location.

 

[bluewraith]

you mean like this

Yep. Guess I misunderstood when you said you wouldn't have to deal with backlash with the DRO.

 

[IndyGunworks]

Yep. Guess I misunderstood when you said you wouldn't have to deal with backlash with the DRO.

AHH i see, i didnt think your post was a response to the DRO. thanks for bringing that up, i had not though that i still have to go past the point of backlash before i reaproach a position w/ the DRO... thats good advice and it probably would have slipped my mind. Ill give you some rep when i can.

 

[top hat 45]

nice job. i'm glad you got the mill back

 

[lovemachine]

If you always approch a location from one direction then you never have to worry about backlash. I always zero my dials and write down the previos adjustment so i can always return to a previous spot. to return to a spot you simply go past it more than whatever amount of backlash the machine has then reapproach the proper location.

Just an FYI, you always want to be going towards the right on the dial. Lock your table, and set into the backlash.

That way if the table moves, the handle gets bumped, etc.., you know that you were going toward the "right/clockwise" direction.

 

[drillsgt]

If your doing a one off job,like gunsmithing,your indicator is your best friend.you get 1 chance to get the job right or it is forever #$%&ed up.

Or know a really good TIG welder

 

[tmkr]

I disagree. ALL machines have backlash of some sort or another. I could probably get my backlash to less than .010 by tightening up the gibs, but thats better suited for when i have the time to take it apart.

If you always approch a location from one direction then you never have to worry about backlash. I always zero my dials and write down the previos adjustment so i can always return to a previous spot. to return to a spot you simply go past it more than whatever amount of backlash the machine has then reapproach the proper location.

ALL machines have backlash period. at least these kind of machines. My understanding is that backlash can only be eliminated w/ ball screws which are not very typical on affordable machinery. I am checking backlash by putting a travel indicator on the machine but against the vise then moving the handle until the needle JUST moves, then counting how many thousands on the dial until the dial begins to move back the other direction.

once i get my DRO installed i wont have to worry about how i approach a measurement though, or even deal w/ backlash because the DRO doesnt care about backlash as it ONLY measures the movement of the table/knee.

brand new jets have around .050 thou of backlash right from the factory. these old indexs and bridgeports have at least a few thousands of backlash when they are new also. its a screw and its imposible to have ZERO backlash and still allow for movement.

I dont think tightening the gibs will reduce the backlash.The backlash is in the screw and nuts.Some machines have a double nut setup that you can adjust to minimize backlashbut you have to be careful and not get them too tight,especially on an older machine.The most wear is usually in the center of the x and y axis,where the machine is used the most.If you set the nuts for minimum backlash in the center of the axis as you travel to the ends things will tighten up where the screw has not been used as much.Same thing happens when adjusting gibs.A small amount of backlash is good,it allows a little room for lube.

 

[IndyGunworks]

.Some machines have a double nut setup that you can adjust to minimize backlash

thats what i meant to say... half nuts maybe?

 

[random_eyes]

I've always enjoyed this fellow's work. I thought of it when you mentioned the expensive tooling. I think he made a dovetail cutter for one of the projects he details.

Making Counter-bores on the Taig Lathe and Mill

 

[Skyhawk]

Have you tried the old file and fit method? Most smith's can do it by hand in less time than you spent setting the mill up to make one cut. Try it, you may be suprised at how easy and quick you can make a very accurate dovetail cut with a good set of files for dove tailing. Brownells have them. However, if you continue to use the mill take little bites at a time out of the metal. Keeps the cutter cooler. Oh, and lots of cutting oil.

 

[IndyGunworks]

Have you tried the old file and fit method? Most smith's can do it by hand in less time than you spent setting the mill up to make one cut. Try it, you may be suprised at how easy and quick you can make a very accurate dovetail cut with a good set of files for dove tailing. Brownells have them. However, if you continue to use the mill take little bites at a time out of the metal. Keeps the cutter cooler. Oh, and lots of cutting oil.

I dont know any smiths that use a file to cut dovetails. I cant imagine it would be very cost effective and the files sure wouldnt last long.

 

[jmdavis984]

[ame]http://www.youtube.com/watch?v=W60yBwzipKA[/ame]

[ame]http://www.youtube.com/watch?v=b43odFm0mrI[/ame]

[ame]http://www.youtube.com/watch?v=wcfAFxsfqA0[/ame]

[ame]http://www.youtube.com/watch?v=wcp97wXg6k8[/ame]

And that's the way it is.

 

[42769vette]

No question about it, if you have a mill its much more cost effective to use it over a hand file