New owner Jet GH-1340W-1 needs help

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ptgord
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New owner Jet GH-1340W-1 needs help

Post by ptgord » Fri Aug 06, 2010 5:56 pm

Had little machine shop class 30+ years ago. Machine appears pretty good so far. Manual is probably weakest link. Any owners of this model to answer questions?

1- had problem with thread dial being frozen due to poor fit. Fixed that problem but now wondering how much pressure should be applied when tightening single screw holding dial assembly. Presume thread dial should be turning any time the feed screw is revolving. How does engaging half nut disengage the thread dial?

2- Did 15" test cut along 1.25" bar in chuck & supported by live center at other end. Measure with caliper showed .002" difference in diameter at each end of cut. Is this acceptable? Of course some of the problem could be in the live center.

3- Many gear changes are impossible without hitting jog button and engaging as chuck is stopping. Is this acceptable until some wear occurs and things loosen up?

Thanks for helping with stupid questions...
Jet GH 1340W-1, Jet JMD 18 mill/drill, Miller 175 mig, Miller Spectrum 625

John Evans
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Re: New owner Jet GH-1340W-1 needs help

Post by John Evans » Fri Aug 06, 2010 6:09 pm

1 The thread dial does not dis-engage ,with 1/2 nuts engaged the carrage is moving at the same rate the lead screw is advancing. Gives the impression that it has dis-engaged.
2 Your .002 is not unheard of over that distance . But .002 is within the range of error for a caliper ,use a mike.
3 Very normal ,I usually rotate the chuck by hand when making gear changes. I do not like the sound of gears grinding.
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Diesel II
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Re: New owner Jet GH-1340W-1 needs help

Post by Diesel II » Fri Aug 06, 2010 6:42 pm

I have a manual I can email it to you. I have the same lathe.
Equipment:Atlas Shaper, Bridgeport Mill, Southbend Heavy 10 Lathe
Prat and Whitney Bench Miller, Jet 13x40 Lathe, Boyar Schultz Surface Grinder

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Falcon67
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Re: New owner Jet GH-1340W-1 needs help

Post by Falcon67 » Fri Aug 06, 2010 10:58 pm

Can't help with 1 or 2, but #3 is pretty common for gear selection type machines. My mill is a gear selectable speed unit and sometimes requires twisting the spindle or jogging to get full gear engagement.
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Davo J
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Re: New owner Jet GH-1340W-1 needs help

Post by Davo J » Sat Aug 07, 2010 12:04 am

I engage ny thread dial just enough so it dosn't push the lead screw over. If it is disengaging when engaging the half nuts it sounds like the half nuts are pushing the lead screw over.

With the test cut it is more than likely the tail stock off centre.
For a quick test you can put a centre in both the head stock and tail stock then bring them together with a 150mm rule in between horizontally. Look down over the rule and it should be square to the lathe ways. If it's not, loosen the tail stock lock then undo the allen head grub screw and adjust it until it sits square.

There is a more precision way called the 2 collar test. It is basically a bar 25mm dia+ between the tail stock and into the chuck. The middle of the bar is machined off to leave a collar on each end. To test the tail stock you machine one collar, then without moving the cross slide move it along and machine the other collar. Measure the 2 and if there the same you have it setup right, if not adjust the tail stock and take another cut.
One way to help with finely adjusting the tail stock doing this test, is to put an indicator onto the backside of the job near the tail stock, that way you know how much your adjusting it.

You can make one of these test bars up and keep it as a lathe tool for setting up for precision work. I only have one but some people have a few different length ones just incase the lathe has inaccuracies along the ways.
If you google lathe 2 collar test you will get a lot of hits.

I never use the jog button on mine. I think it is to hard on the motor and the gear train, so like is said above I turn the chuck by hand.

Dave

ptgord
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Re: New owner Jet GH-1340W-1 needs help

Post by ptgord » Sat Aug 07, 2010 9:25 pm

Thanks to everyone for the help.

Today my brain engaged & I realized that when the 1/2 nut is engaged you travel at the same speed so dial quits turning. duh!

Rotating chuck by hand sounds much more humane than jog button.

Haven't purchased mike yet. Calipers were from class 30 years ago as are some other tools.

My lathe came with free QC tool post set but won't fit on existing bolt. QC has much larger bolt. Best way to adapt? Make new block with bolt hole to fit new bolt size. QC came with base but is much larger & will require quite a bit of machining. Also considering changing bolt also when I make new block so that future adapters would be easier to thread. BTW the QC looks very sharp. Much finer finish than some parts of the lathe. Set includes 5 or 6 tool holders.
Jet GH 1340W-1, Jet JMD 18 mill/drill, Miller 175 mig, Miller Spectrum 625

John Evans
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Re: New owner Jet GH-1340W-1 needs help

Post by John Evans » Sat Aug 07, 2010 9:39 pm

If you are refering to the T nut for the QC post it is normal to modify to fit your compound. That's why we all have mills also. Don't we ?? :roll:
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steamin10
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Re: New owner Jet GH-1340W-1 needs help

Post by steamin10 » Mon Aug 09, 2010 12:59 am

I had to heavily modify my QC Phase post for my poor SB lathe. First the center bolt, then change all the locking sets with goood ones. ( The originals strip very quickly being too soft. They are a bear to get out if you squish the hex.) And finally I used a sanding block on just about all the edges that were so sharp I would get nicked handling them. I used a rubber body block with 400 grit dry, and worked the edges a bit. It ruined the dark finish, but they are comfortable to handle now. I also made a spacer to pick the block up some, so the holders weren't so far up on the adjustment screw. I am happy with them.
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ptgord
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Re: New owner Jet GH-1340W-1 needs help

Post by ptgord » Sat Aug 14, 2010 6:39 pm

Some progress & more questions. Trying to add photos to clarify.

Modified T-post for QC but concerned about overhang of block. T-post contact with block is only about 1.5 x 3 inches while block is about 3 x 3.5 inches. Seems rigid enough so far but wondering if I need to mill bigger T-slot so I can make T-post much larger allowing full contact of block.
HSM-3.jpg[/attachment First attempt at threading to allow replaceable plastic face on brass/plastic hammer head. Still considering what kind of handle to use. When cutting metric threads where this machine doesn't allow disengaging half-nut, how should you stop at the end of the cut so that you can back out and return to the beginning? Should you stop the lathe, back out, then reverse to the beginning? [attachment=1]HSM-2.jpg
HSM-1.jpg
Finally after following discussion on seating, I decided to incorporate sitting area as part of my tool cabinet for lathe & mill.
HSM-4.jpg
Attachments
HSM-3.jpg
HSM-2.jpg
Jet GH 1340W-1, Jet JMD 18 mill/drill, Miller 175 mig, Miller Spectrum 625

ptgord
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Joined: Wed Jan 13, 2010 9:20 pm
Location: AR

Re: New owner Jet GH-1340W-1 needs help

Post by ptgord » Sat Aug 14, 2010 6:44 pm

Whoops! Lost part of my text. Two of the pics are attempt at brass/plastic hammer head with replaceable plastic head. First attempt at threading.
Jet GH 1340W-1, Jet JMD 18 mill/drill, Miller 175 mig, Miller Spectrum 625

EdK
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Re: New owner Jet GH-1340W-1 needs help

Post by EdK » Sat Aug 14, 2010 6:57 pm

ptgord,

I can't tell for sure from the picture but it looks like your T-nut is above the surface of the compound. It should be slightly below the surface of the compound so the bottom of the tool post sits on the compound surface and not the T-nut.

Ed
Vectrax 14x40 lathe, Enco RF-45 clone mill, MillerMatic 180 MIG.

millman52
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Re: New owner Jet GH-1340W-1 needs help

Post by millman52 » Sat Aug 14, 2010 7:24 pm

EdK wrote:ptgord,

I can't tell for sure from the picture but it looks like your T-nut is above the surface of the compound. It should be slightly below the surface of the compound so the bottom of the tool post sits on the compound surface and not the T-nut.

Ed
I thought the same thing, I saved the picture & enlarged it till it was becoming blurry. I couldn't tell for sure but it looks to me like it is above the compound.

If it is I agree the top of the "T" nut needs to be milled of to a point it is several thou below the top surface of the compound.

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