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Jet 13 x 40 gh cross slide angles

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jmh8743

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#1
As you know the protractor on the cross slide is difficult to use and crudely stamped. Not only that it does not have cardinal points and lacks a vernier. Maybe this will help.


lathe 008a.JPG
1. Locate roughly the rotational centerline of the compound and estimate 90^. Set the DI on zero at that point. Then traverse the cross slide, say 3" or 6" on the DRO. Slowly adjusting 'til you get to zero all the way. Any mis-estimate of the compound rotation center will be corrected by trial and error. Mark a cardinal point for 90^.
lathe 015.jpg

OK how much is good 'nuff. Well say you got 0.0015 in 3. Well the sin = tan for small angles. So .0015/3 = 0.0005. And the Arctan of .0005 is 0.0286 deg which = 0^01'45". We can get about 20" accuracy. So I quit at 0.0005" in 3". 0.0005/3 = 0.00016
Arctan 0.00016 = 0^00'34". We can get a little better if desired. BUT
2. Then we have a good reference. So insert a protractor in the tailstock and set zero. Then align the tool post to the protractor which is set at 90^ and tighten tool post. Now the tool post is aligned with the cross slide/compound slide. The one you see here came from Bridge City Tool Works (about 15 yrs ago)


lathe 017.jpg


3. Back the saddle away and set the desired angle. More to come. Lunch time.

lathe 008a.JPG lathe 015.jpg lathe 017.jpg
 
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jmh8743

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#2
Let me try to be as succinct as possible. So the cross and the compound are parallel to one another.

3. Set the protractor to the desired compound angle.

4. Return the saddle and rotate the compound (tool post) to the protractor angle.

lathe 019.jpg
5. Now the compound is to the angle desired. Here 22^30'00" (+ or - 15" of angle).

6 If desired you can rotate your protractor back to 0^00'00" and set the tool post to that.


lathe 020.jpg

so your compound is at the desired angle and the tool post 90^ to ways. Or you can leave the tool post as is.

Any questions? hope this helps someone.

Mike

lathe 019.jpg lathe 020.jpg
 

darkzero

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#3
Mike, thank you very much for sharing! I've always wondered how others do it, keep forgetting to make a post about it.

Do they still make that protractor you have & did you modify it to fit your TS or is that how it's made? I like it & could find other uses for it.

At least you have a scale on your cross slide. I hate mine & of course it's not very accurate at all. The witness mark is off about just under a degree.

Here's how I do it.....


I use a SS slide protractor that I got from Grizzly for $6. The Starrett 47 Universal Bevel is $100!
Img_7114_zps9eedafa4.jpg


I have just been using a piece of flat stock against the crosslide to align the angle. Haven't checked how accurate this method is yet but it's been working fine for me.
IMG_7121_zps6e499594.jpg


Here's my sorry excuse for a scale.
Img_7125_zps45b9001b.jpg
 

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jmh8743

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#4
Hey Will,

look at http://www.bridgecitytools.com/ and see if they have it. I bought it for my JET mill-drill. the shank is 3/8. Look closely and you will see a collet in the tailstock. I had a lot of issues with my lathe so this was just a part. You are right 1^. i promise you that I could make a "preacher" (triangle) with the mill and it would check very close. I can read the vernier directly to one minute and easily interpolate to 1/2 minute.

It took me a while to get it straight. Transferring to the toolpost came in a vision. If the compound was thought-out we could have a direct scale and vernier. I dont think these machines are made at the same place.

Finally, you could mirror my procedure and use a 3 jaw chuck in the headstock. The protractor is the issue. Of course, if all our machines were the same, I could devise a vernier.

This is a good venue for us all. Tony thought up a good idea. Kinda like a JET users group. Hee Hee.

Mike
Remlap, AL

PS Will, that is an excellent protractor. You are probably very close. Bridge City tools are proud of their tools. If you could transfer similar to some known, it would be much better than mine. A simple "holder" on a tool bar would work. Then I promise you can be within 15" of angle.
 

darkzero

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#5
Hey Will,

look at http://www.bridgecitytools.com/ and see if they have it. I bought it for my JET mill-drill. the shank is 3/8. Look closely and you will see a collet in the tailstock. I had a lot of issues with my lathe so this was just a part. You are right 1^. i promise you that I could make a "preacher" (triangle) with the mill and it would check very close. I can read the vernier directly to one minute and easily interpolate to 1/2 minute.

It took me a while to get it straight. Transferring to the toolpost came in a vision. If the compound was thought-out we could have a direct scale and vernier. I dont think these machines are made at the same place.

Finally, you could mirror my procedure and use a 3 jaw chuck in the headstock. The protractor is the issue. Of course, if all our machines were the same, I could devise a vernier.

This is a good venue for us all. Tony thought up a good idea. Kinda like a JET users group. Hee Hee.

Mike
Remlap, AL

PS Will, that is an excellent protractor. You are probably very close. Bridge City tools are proud of their tools. If you could transfer similar to some known, it would be much better than mine. A simple "holder" on a tool bar would work. Then I promise you can be within 15" of angle.
Mike, glad you got it figured out.

Man you weren't kidding, I checked out their site & man do they offer some very very nice stuff! The quality & finish are amazing. Pretty expensive but I can see why! Saving that link for sure!

That's exactly what I was thinking, for use on the mill. I found the protractor but unfortunately it's in their discontinued section. However I found one on ebay for $100 buy it now. Seller says it's a 1998 limited edition signature series no. 1100 of 3500. Normally I don'y buy personalized tools but it just has the prev owner's initialls stamped on the brass knob under the no. No box or paperwork but it's pretty much brand new & I had to have it so I bought it! I love quality tools so I have no problem paying for this one. There were a couple of others for auction.

Thanks again Mike for making me spend more money. :))
 

barrydc1

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There were a couple of others for auction.
I couldn't find any on Bridge City or E-bay. Did you have a link. This is a great way to set angles quickly and with good accuracy it seems to me. I'd love to have one too, but can't find one or even something like it. Might have to consider making one, but need to get my lathe straightened out first.

Thanks for the great post here, mike!

P.S. I read your entire saga with the Jet 13x40 and just posted my own similar problem, you've helped me alot, but issue seems slightly different as the spindle has some rotation to it.
 

darkzero

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#7
I couldn't find any on Bridge City or E-bay. Did you have a link. This is a great way to set angles quickly and with good accuracy it seems to me. I'd love to have one too, but can't find one or even something like it. Might have to consider making one, but need to get my lathe straightened out first.

Thanks for the great post here, mike!

P.S. I read your entire saga with the Jet 13x40 and just posted my own similar problem, you've helped me alot, but issue seems slightly different as the spindle has some rotation to it.
When I purchased mine on ebay there were 4-5 other auctions at the time for them. The one I got was the only buy it now available at the time & it was priced at $99 + $10 shipping. It was in pristine condition & priced higher since it was a numbered limited edition signature series (which didn't matter to me). Bridge City's site lists them as originally at $89 on their discontinued page. The others were auctions but I didn't want to mess with them & rather pay more for a better condition one. Those auctions ended up at around $60- $100.

I just searched & didn't find any but I'm sure more may pop up one day, just have to keep checking back. I searched "MP-8 Machine Protractor" on google & is what led me to the ebay auctions.

I got one of those signature series ones but it did not come with the wooden case. I just got me a blow molded case & cut the foam insert out for it to fit.


Img_7299_zpsa02dac64.jpg

IMG_7300_zpse346b0db.jpg
 

barrydc1

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That sure is a nice idea. How come they aren't more common? Your case is also really nice. I'll have to remember that idea. Do you have a source on the blow-molded cases? I imagine I could just google it unless you have a source with a great price and good quality you already think is the best. Thanks again, I'll have to keep checking e-bay. I did, by the way, find one on e-bay that had just sold for $180 w/ $10 shipping.

Barry
 

jmh8743

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Barry,

make one if you can't find it.
1) put a ground bar in the tail stock , preferably in a collet.
2) then get the protractor Will has against the tool post.

You will get cloooose angles as good as 10 seconds with the "transfer" procedure.

glad I can help. Sorry you have JET problems. I think it is a corporate issue. My follow rest and steady were for the wrong machine.

Mike

back in Cullman not at shop, hello Will
 

barrydc1

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Not sure I'm following you. Put what protractor against the toolpost, and how does the ground bar in the collet figure in? Sorry, just not seeing it.

Barry
 

jmh8743

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Sorry I was not succinct. Look at post #3. Great protractor.

Insert a ground bar into tail stock.
take a Sterret 47 bevel similar to darkzero's and perform the transfer like I did.
measure to the ground bar and the tool post.

Perform the same procedure I did. Use that bevel to measure. If this isn't enough I'll draw a sketch.

same principle. Read my first 2 posts again, only substitute the Sterret in lieu on the Bridge City if you can't find one.

get the compound parallel to the cross slide.
mike
 

darkzero

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#12
That sure is a nice idea. How come they aren't more common? Your case is also really nice. I'll have to remember that idea. Do you have a source on the blow-molded cases? I imagine I could just google it unless you have a source with a great price and good quality you already think is the best. Thanks again, I'll have to keep checking e-bay. I did, by the way, find one on e-bay that had just sold for $180 w/ $10 shipping.

Barry
Thanks Barry. I don't have a cheap source for the cases. Originally I was just going to get a handgun case locally but changed my mind. Plenty on Amazon too for cheap. After searching I found out that blow molded cases are not cheap. I choose to get a larger size so that the protractor would fit in it not matter what angle it was set at rather than having to set back to 90° to store it. Mine is made by PFC, purchased directly from the manufacturer on ebay. Cost about 1/4 of the price of what I paid for the protractor but for me it was well worth the investment.
 

jmh8743

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#13
Barry,

This is 2 steps.
get the compound 90deg with a DI. First.

set the tool post to 90 deg with protractor set at 90
One leg against ground bar
The other against tool post.

NOW the CS and tool post are parallel.

this is step one. Do not feel bad it took me 2 yrs to work this out.
once you can make this happen, use a try square for now, we'll go to step 2.

i'm glad to help.
mike
 
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