Some Lathe Stuff

[deere2210]

Those are sweet, turned out nice.
Why don't you engrave that kind of stuff yourself with your cnc mill?

Thanks! I don't get the same quality as I do with the laser. I've used a .02 and .01 engraver and end up with small tool path lines that are visible. The laser doesn't leave any visible lines. Plus, on convex/concave items, I need to figure out the geometry first where the laser has a little more tolerance.. Makes setup easier.. It's still x/y/z but DOC isn't as critical. I'll post a couple other things I've done with it.. My kids have worn me out on engraving aluminum water bottles and dog tags for school..

 

[deere2210]

Here's a quick one I did on chrome for a guy that just sent me pictures of it on his bike.. Sorry for the red tint on one.. It's hard to take pictures of chrome with the reflections coming off..

 

[deere2210]

Started work milling out the first part of the forward controls. Everything went fine.. except, I reamed the hole to 1" with a 1" reamer.. I ended up buying a 1" oillite bronze bushing from McMaster.. After I reamed the hole, it was too big and the bushing just slid in, no press fit.. Before I reamed it, the bushing clearly wouldn't fit. I undersized the hole by .01 and then reamed. Any ideas? Scratching my head on this one..

 

[rmuell01]

Before I reamed it, the bushing clearly wouldn't fit. I undersized the hole by .01 and then reamed. Any ideas? Scratching my head on this one..


[/IMG]

Yep. put some more metal on it. Knurl it and it will expand and may fit.

 

[hunter1151]

Did I understand that you reamed a 1" hole and used a 1" bushing..........reamers rarely run true and on a 1" hole I would have left .015" a side so the reamer can cut a good chip. What rpm did you run the reamer and what kind of feed-rate did you have? If you have the reamer perfectly straight and you have the right speeds and feeds you would still be lucky if it cut right on size. For one-of press fits I always bore the hole........if I am running production you have test parts you can play with to see where the reamer is cutting and adjust for it. What did your bushing measure?

 

[OccupantRJ]

Did I understand that you reamed a 1" hole and used a 1" bushing..........reamers rarely run true and on a 1" hole I would have left .015" a side so the reamer can cut a good chip. What rpm did you run the reamer and what kind of feed-rate did you have? If you have the reamer perfectly straight and you have the right speeds and feeds you would still be lucky if it cut right on size. For one-of press fits I always bore the hole........if I am running production you have test parts you can play with to see where the reamer is cutting and adjust for it. What did your bushing measure?

I totally agree with this. Deere, see my post #92 about not beating yourself up. Some things in machining can be very frustrating, to say the least. Math says one thing, reality is another. I also prefer a boring bar when possible, as reamers can have a wild side to them, each metal and conditions being different. I always hand ream bushings after pressing, using hand driven tools, usually an adjustable reamer. These can be used on bores also to get that just right fit without putting your faith in a one shot attempt. I make the hole first when possible, and the male part second. You can knurl the bushing OD for a press fit in your application, by making an expandable arbor to hold it for the operation. This is the true skill in machining, controlling the cut, as that's what it is all about.

 

[Kevin54]

I second (maybe third) for the knurling. If your hole is way oversize, which it looks like it is, you may want to make the piece over and count this one as a learning experience. For a 1" hole like that, I would have probably bored it. But even if I reamed it, I would have ran the rpm's way down and hand fed the reamer through. Once you are through, shut the machine off, then pull the reamer back up. Sometimes if you get harmonics in the reamer when reaming, it will cut both ways, going in and coming up, and you end up with an oversized hole.

You have quite a bit of length on your reamer too, so chances are you will get vibration / harmonics coming from it. Once the vibration starts, it's hard to maintain a round, up to size hole.

 

[Nelson58]

What would you guys suggest that he do now to correct this?

Larger OD bushing?


Nelson

 

[deere2210]

I think I am going to redo it.. I hand fed the reamer.. Ran it at 770 RPMs based on a web site I found. Does that sound right? Hand fed it at ~12IPM.. One thing I did do is ran it down and back up and one more time down/up.. Sounds like one time is all you do and then not on the upstroke.

Not completely following the knurling piece.. Is the idea the knurling raises the surface a couple thousand? I think it still will not enough for press fit so probably better to do it over.. I learned some stuff as I was doing it and will mark this one down as learning..

The next one I will use a boring bar.. Thinking of drilling it up to .75, and then working it down slowly with the bar.. What kinds of speeds/feeds for the boring head/bar? Again, thanks all for the feedback and sharing of experience!

 

[deere2210]

This is the true skill in machining, controlling the cut, as that's what it is all about.

Occupant, I'm learning how true that statement is.. I think I am going to make a sign out of that quote and hang it on my wall..

 

[Nelson58]

I think I am going to redo it.. I hand fed the reamer.. Ran it at 770 RPMs based on a web site I found. Does that sound right? Hand fed it at ~12IPM.. One thing I did do is ran it down and back up and one more time down/up.. Sounds like one time is all you do and then not on the upstroke.

Not completely following the knurling piece.. Is the idea the knurling raises the surface a couple thousand? I think it still will not enough for press fit so probably better to do it over.. I learned some stuff as I was doing it and will mark this one down as learning..

The next one I will use a boring bar.. Thinking of drilling it up to .75, and then working it down slowly with the bar.. What kinds of speeds/feeds for the boring head/bar? Again, thanks all for the feedback and sharing of experience!

I think if you ream in and out you are taking off too much metal- once is enough, especially for a press fit.

Nelson

 

[OccupantRJ]

Occupant, I'm learning how true that statement is.. I think I am going to make a sign out of that quote and hang it on my wall..

Well, for a sign, let me revise it a little.

The true skill in machining is controlling the cut, as that's what it is all about.

I would either knurl, make a new bushing, or buy another bushing with a larger OD and turn it to size. I always waste the simplest and most troublefree, inexpensive part. Keeping a standard on the bushing in a production setting would be wise, but for a one off part that I will be using, I don't concern myself with it too much. Seems everything I make or repair is custom, anyway, as most of my work is on the fly, with no drawings other than my hand sketches.

 

[hunter1151]

770 rpm for a 1" reamer is more than 7 times what it should have been. If I would have had to use the reamer, I would have turned it 60-100 rpm max plenty of feed and never in and out more then once.........because of the usual run out of the reamer.

Rpm on a boring head will depend on the geometry of your boring bar you use in the boring head. I assume you will be using a Criterion or some other similar boring head, so if the boring bar insert or whatever boring bar you use is really sharp you should be able to turn it up to between 500-1200 rpm and get a killer finish if everything is right. I suggest you leave plenty of material in the hole and experiment with the rpm to get a good finish. If it chatters you are going too fast. You will need to sneak up on the final bore.....when you are getting close you will want to take a spring pass, with the boring head and then set for the final bore.

 

[OccupantRJ]

What would you guys suggest that he do now to correct this?

Larger OD bushing?


Nelson

Knurling, stippling, or a larger OD bushing, in my opinion. No need to have to remachine the whole part, for a manually operated mechanism, other than personal pride, as long as the end result is achieved.

 

[Kevin54]

If you have the bronze to machine one, you can either make a new bushing or if you don't have the material to make one give the knurling a try. You can increase the diameter by .015 give or take a few with a good diamond knurl.

If your bore on the aluminum part isn't too much oversize, you can swedge the hole down with a large ball bearing. Place it on each side of the hole and rap it with a hammer. You can take a pointed punch and go around the inside diameter of the hole as many times as you can and put ***** points in the hole. There's a lot of things you can do to cover a mistake and it's done by the best of them. That's one reason I won't fly

As far as boring it, if you go that route, you can drill it larger than .75. I'd drill it at least to .937 or 15/16" and bore from there.

 

[hunter1151]

You know I got to thinking that you bought oilite which is sintered, I'm not real sure you could knurl that up and I don't know how much shock it would take if you started hammering on it to stipple it. That stuff tends to be a little brittle...........just my 2 cents worth.

 

[deere2210]

I went ahead and ran it again.. I profiled everything out, and got the boring bar setup. I haven't flipped it and saved all the settings and can finish it one night this week. I wanted to redo it as this is a learning exercise for me and this helps reinforce the concepts.. Plus, the boring bar made me step away from CAM and right a little g-code (G85) by hand which definitely makes you learn the stuff. I ran the boring bar down and got it setup.. Wow, those drill bits walk all over.. hole was no where near straight.

So here's the question.. I mic'd the oilite bushing and is shows 1.003 I can either turn the bushing down or make the hole large enough to press fit it without turning down.. How much difference in size should the piece being pressed into the hole be?

Here's the piece after running the boring bar.. great finish with the bar.. It's currently sitting at .8 diam.. Still need to finish it out to final size..
Settings 1200 RPM, 2.4 IPM

 

[deere2210]

You know I got to thinking that you bought oilite which is sintered, I'm not real sure you could knurl that up and I don't know how much shock it would take if you started hammering on it to stipple it. That stuff tends to be a little brittle...........just my 2 cents worth.

Good to know.. I've never worked with it before.. I'm thinking instead of turning it down, making the hole large enough to match the bushing for a press fit..

 

[Ironhorse]

I started off with a 3 axis Tormach to replace the Bridgeport.. Good little mill.. Someday hoping to get the 4th axis for it, but will see.. I also had an Enco 9x20 lathe that I cut my teeth on.. Decided to go with a Haas TL-2 as a replacement.. Ability to easily cut threads has been great.. Solidworks for drawing stuff out, Sprutcam Cam for mill, and OneCNC for lathe plus usually a lot of hand editing. Day job is in software industry so that helped on the programming.. No previous experience in machinining so for the last three years I have read every book I can find at night on the subject and just chucked stuff up and went at it..

I sold my Bridgeport and bought a Tormach...the sameone you have...tried it for one job...wanted my bridgeport back..( you can tilt the head ) sold the Tormach on Ebay last month...it got shipping damage to the back motor cover so it is back in my shop as of Friday...new motor cover is $200....so here is the question do you like it better then your bridgeport? how fast are you running the spindle? I know the spindle speed is adj off the contol box...I really did not get that part of the mill and about ripped out the bit. thanks in advance...if it turns out to be a good mill on your word I will put it in the home garage...I saved 80" for it of wall space.

 

[OccupantRJ]

Good to know.. I've never worked with it before.. I'm thinking instead of turning it down, making the hole large enough to match the bushing for a press fit..

Here you go.

http://www.oilite.com/PDFs/castBronze_designData.pdf

 

[Kevin54]

So here's the question.. I mic'd the oilite bushing and is shows 1.003 I can either turn the bushing down or make the hole large enough to press fit it without turning down.. How much difference in size should the piece being pressed into the hole be?

Did you buy the Oilite this size? If you did, is the O.D. perfectly round? By that I mean did you mic it top to bottom and all around the diameter? If it is round, then bore to bushing. If it is not perfectly round, then turn the bushing to where it is round, then bore to bushing.

 

[hunter1151]

Here you go.

http://www.oilite.com/PDFs/castBronze_designData.pdf

I guess I stand corrected...........I assumed that all "oilite" bearing material was sintered which would allow for the oil impregnation.

 

[deere2210]

I sold my Bridgeport and bought a Tormach...the sameone you have...tried it for one job...wanted my bridgeport back..( you can tilt the head ) sold the Tormach on Ebay last month...it got shipping damage to the back motor cover so it is back in my shop as of Friday...new motor cover is $200....so here is the question do you like it better then your bridgeport? how fast are you running the spindle? I know the spindle speed is adj off the contol box...I really did not get that part of the mill and about ripped out the bit. thanks in advance...if it turns out to be a good mill on your word I will put it in the home garage...I saved 80" for it of wall space.

I really liked my Bridgeport. I sold it about a month ago since after I got the Tormach I didn't use it as much and was taking up floor space. I've had the Tormach coming up on two years now.. I really like it now more than the Bridgeport. I didn't come from a machining background, so the easier part for me was figuring out the CAD/CAM software stuff. The Tormach has proven to be very good for everything I've thrown at it. It's rigid, holds a tolerance, etc.. The coolant system is a little iffy and could use some rework but it's a good machine. Sure some day, I hope to get a small biz going and buy a Haas VF3 or something similar but for prototyping it's been awesome.. Sprutcam was a little bit of a challenge since the documentation was written by Russians for Russians and then translated to English but I think I'm getting it pretty well down. At this point, I can't imagine not having it around. My recommendation would be to definitely make space for it in your garage and give it a try.

 

[deere2210]

Did you buy the Oilite this size? If you did, is the O.D. perfectly round? By that I mean did you mic it top to bottom and all around the diameter? If it is round, then bore to bushing. If it is not perfectly round, then turn the bushing to where it is round, then bore to bushing.

Kevin, I read your post and immediately hit me that I should have done multiple measurements like you said.. I'll remeasure it tomorrow night and confirm.

 

[deere2210]

Here you go.

http://www.oilite.com/PDFs/castBronze_designData.pdf

So, if I read this correctly.. A 1" bushing has +.002-.003 tolerance.. And the recommend press fit for a 1" O.D. is .001-.003. So I would bore the female hole to 1.005. This is based on the bushing being symmetric and the diameter being constant the entire length..

 

[Ironhorse]

I really liked my Bridgeport. I sold it about a month ago since after I got the Tormach I didn't use it as much and was taking up floor space. I've had the Tormach coming up on two years now.. I really like it now more than the Bridgeport. I didn't come from a machining background, so the easier part for me was figuring out the CAD/CAM software stuff. The Tormach has proven to be very good for everything I've thrown at it. It's rigid, holds a tolerance, etc.. The coolant system is a little iffy and could use some rework but it's a good machine. Sure some day, I hope to get a small biz going and buy a Haas VF3 or something similar but for prototyping it's been awesome.. Sprutcam was a little bit of a challenge since the documentation was written by Russians for Russians and then translated to English but I think I'm getting it pretty well down. At this point, I can't imagine not having it around. My recommendation would be to definitely make space for it in your garage and give it a try.

Thanks that is what I needed to hear...after selling it and getting it back Friday I thought it might be fate..lol. Sad it had to get transported to SC then back. I did run syn motor oil mixed with syn coolent thru the pump for coolent and messy but oiled the table and vice. So now that you have played with it for two years...you can help me with mine? I will order the parts Monday and move it to the garage next Monday. As far as programming it seemed a pretty simple ( plus had a little picture of setup on the upper right of the screen). Mine has a 10key pad as well as the handcontrol, mouse, and keyboard...what is that for?

thanks

 

[OccupantRJ]

Another thing you will want to do is to chamfer the outer edges of the hole through your part, to allow the bushing to press in without broaching material off of the bushing OD.

 

[hunter1151]

You didn't mean to bore the hole 1.005 did you?? That would be .002 too big. Did you mean 1.0005?

 

[deere2210]

You didn't mean to bore the hole 1.005 did you?? That would be .002 too big. Did you mean 1.0005?

The oilite PDF doc said they have a +.002-.003 tolerance on the O.D... I mic'd it and it is showing the O.D. as 1.003. On page 2 of the doc it shows a press fit for a 1" O.D. being between .001-.003.. I was thinking of splitting the difference and using .002. So I added the .002 to the busing O.D. (1.003) to come up with the 1.005. Am I looking at this the right way?

 

[OccupantRJ]

So, if I read this correctly.. A 1" bushing has +.002-.003 tolerance.. And the recommend press fit for a 1" O.D. is .001-.003. So I would bore the female hole to 1.005. This is based on the bushing being symmetric and the diameter being constant the entire length..

Simply measure the bushing OD, then make your part bore .002 smaller, giving a press fit of .002. Be careful of tolerances. +.002 -003 is not the same as .002 to .003. The first figures would indicate a part can be as much as 2 thousandths oversize, or as much as 3 thousandths undersize, and be compliant with design specs. If you were to bore the hole to 1.005, your bushing, which tops out at a possible 1.003 OD, would once again fall through the hole.

 

[OccupantRJ]

The oilite PDF doc said they have a +.002-.003 tolerance on the O.D... I mic'd it and it is showing the O.D. as 1.003. On page 2 of the doc it shows a press fit for a 1" O.D. being between .001-.003.. I was thinking of splitting the difference and using .002. So I added the .002 to the busing O.D. (1.003) to come up with the 1.005. Am I looking at this the right way?

No, take away from the bushing diameter for a press fit.

 

[Kevin54]

As Occupant stated, mic your bushing, then take away .002 for your bore in your part. This would put your bore at 1.001.

Then as stated, chamfer your bushing and your part. The reason I like the chamfer on the bushing going in is that so it doesn't shear material out of the hole. If it were a hardened bushing with a razor sharp edge and it started shearing, chances are you would have a crooked bushing once in the part. You can also turn down a small portion of the bushing, maybe .100-.150 back and just enough on the diameter for a slip fit into your bore. This allows for straight alignment when starting to press in.

 

[deere2210]

Got it, thanks! picture definitely helped.. How big a chamfer on the part and bushing.. Does .01 sound right?.. Jut small enough to break the edge?

 

[Kevin54]

Got it, thanks! picture definitely helped.. How big a chamfer on the part and bushing.. Does .01 sound right?.. Jut small enough to break the edge?

Just enough to break the edge will be fine. As long as it's not razor sharp. It can be a chamfer or it can be a radius. Hitting it with a file would work while you have it in the lathe.

 

[Nelson58]

How do you plan to press the bushing in to insure it goes it straight?

Nelson

 

[deere2210]

Okay, finished the boring bar.. Looks spot on at 1.001 with telescoping gauge and mic.. Ran a small chamfer around the part.. Will face the back off tomorrow night and turn down the bushing.. Also, thinking of turning this little mandrel to help push it in..?

 

[OccupantRJ]

Yes, make the mandrel, but make it about 6 inches long, as it is easier to tell if you have it lined up straight before pressing. Make the small diameter several thousandths smaller than a slip fit, or it will lock up in the bushing during pressing, as the bushing will swage smaller on the ID during pressing. This is another reason to ream the ID of the bushing after pressing.

 

[hunter1151]

Yes, make the mandrel, but make it about 6 inches long, as it is easier to tell if you have it lined up straight before pressing. Make the small diameter several thousandths smaller than a slip fit, or it will lock up in the bushing during pressing, as the bushing will swage smaller on the ID during pressing. This is another reason to ream the ID of the bushing after pressing.

Right on........carefully ream it after you press fit it.

 

[isaac338]

deere2210, what Tormach is that? What size is the work envelope?

 

[deere2210]

deere2210, what Tormach is that? What size is the work envelope?

It's the 1100. Below are the basic specs.. I have the little splash guards that come with it setup on the ends of the table which restrict it down, but they just unbolt and come off to lay longer pieces on the table.

Table Size: 34" x 9.5"
Table Slots: 3 Slots 5/8"
Travel: 18" x 9.5" x 16.25" (X,Y,Z)
Spindle Nose to Table: 17" maximum