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JET JTM-4VS-1 Knee Mill ~ Z-Axis Knee Powerfeed

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Scott(GA)

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#1
I am trying to install a JET 350196 Z-Axis Knee Powerfeed on a JET JTM-4VS-1 Vertical Mill.

The Powerfeed came with a bracket kit for the Limit Switch assembly that seems inadequate. However, it wouldn't be the first time I've looked at something and missed the obvious. I was wondering if anyone had a JET Knee Mill with a Z-Axis Knee Powerfeed. If so, pictures of the Limit Switch Assembly would be appreciated.

Scott
 

kd4gij

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#2
I don't have a jet. But that power feed is just a rebadged import like Algin or Bestline. Post a picture of what you have and I can help. There isn't much force on the limit switch as it is activated by the spring plungers.
 

Scott(GA)

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#3
20180510-04.jpg

Here's an attempt to show where I think I'd have to put the channel that holds the Limit Switch stops. The machines I have seen Z-Axis installation videos of have a pretty good flat spot right next to the Knee. This machine has a more "organic" transition that makes putting the stops right next to the Knee problematic ...or at least I haven't figured out how to do it so far.

Link to a video of the Z-Axis Powerfeed's controls being exercised.

Scott
 

Scott(GA)

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#4
20180510-05.jpg

Bracket the Limit Switch is supposed to mount on.




20180510-06.jpg

An attempt to show how the Limit Switch would mount on the Bracket.




20180510-07.jpg

The Bracket included in the kit cannot bring the Limit Switch anywhere close to where the Aluminum Channel will hold the Limit Switches.


Scott
 

JimDawson

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#5
You could set it up like mine. The limit switch housing/cable is coiled up with a zip-tie around it and it hangs from the powerfeed. If you're a bit careful, you really don't need the limits. I just have a set of marks on my knee and column to tell me where the bottom is, I just stop before I reach bottom, and if I do need to go all the way to the bottom, I hand crank it the last 1/4''or so. The top is really no problem at all, you'll proabaly run into the quill before you run out of threads on the lift screw.
 

Scott(GA)

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#6
You could set it up like mine. The limit switch housing/cable is coiled up with a zip-tie around it and it hangs from the powerfeed. If you're a bit careful, you really don't need the limits. I just have a set of marks on my knee and column to tell me where the bottom is, I just stop before I reach bottom, and if I do need to go all the way to the bottom, I hand crank it the last 1/4''or so. The top is really no problem at all, you'll proabaly run into the quill before you run out of threads on the lift screw.
Jim,

Your approach does have merit... however, if possible, I try to make my stuff as "Scott-Proof" as possible.
Ha!

Best regards,

Scott
 

mksj

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#7
This was previously posted, the installs are pretty much the same independent of the mill brand. My mill has the channel raised on two round tubes with a bolt through the center. The switch is mounted on the knee. You should have gotten two sections of channel that are connected together to give you enough travel for the stops. The provided channel was flimsy, so I discarded it for a single piece of 80/20 aluminum channel. It is mounted the same way, the channel and stop bolts were slightly modified to fit the new channel.

Old channel with standoff spacer.
20161121_211145.jpg

Fabricated new spacers and single piece channel.
20161121_211217.jpg 20161128_081451.jpg

Switch mount.
Mount.jpg
 

Silverbullet

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#8
I'd have not been smart like you and would have bought new limit switches and wired them top and bottom. Good job using what you had.
 

Scott(GA)

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#9
Thanks to all who have posted so far...

This JET branded item has a price that reflects some "added value" from the Align Powerfeeds (see LINK - it appears to be identical to the JET). It was one of the reasons I purchase a "JET" Powerfeed. I thought it would be delivered customized for a JET Mill.

I'm confident that JET is using a different Bracket to mount the Powerfeed on the machines that they ship with this option installed. That's one of the reasons I initially asked for a picture from someone that has a JET machine. I'll be giving JET a call today to ask about this.
 

Scott(GA)

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#10
I had a nice chat with Mary at JET's Metalworking Technical Support this morning. I explained my problem with the Limit Switch mounting hardware and asked if it would be possible to get pictures of how JET mounted this device at their distribution center. I followed up with an email

About an hour ago I got a reply email with 3 images of a JET Mill with the Z-Axis Limit Switch mounted. This confirmed my theory that JET had "special" brackets available for their distribution center's use.



350196 KNEE POWERFEED INSTALLED(1).jpg

350196 KNEE POWERFEED INSTALLED(2).jpg

350196 KNEE POWERFEED INSTALLED(3).jpg

I have sent a reply to Mary thanking her for the images and asking if the Z-Axis Limit Switch hardware would be available to someone (me) who had purchased JET Powerfeeds & a JET Mill.

I am hoping I will get an affirmative reply and this is what I would use to mount the Z-Axis Limit Switch assembly. If not, I am sure that I can replicate it but why reinvent the wheel?

Scott
 

Scott(GA)

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#11
Got a couple of emails this afternoon from Mary & JET Technical Support. She is arranging for the JET Distribution Center Brackets/Hardware to be sent to me.

All JET wanted was a receipt showing where I had bought the Powerfeeds from, my mailing address & phone contact info.

I am extremely pleased with JET's (and Mary's!) response. My only concern is that I'm doing this on a Friday afternoon. I've found that the most sincere customer service on a Friday afternoon often goes pear-shaped over the weekend and the process must be repeated early in the following week.

Hopefully the brackets/hardware will be shipped without further input by me.

Scott
 

PT Doc

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#12
Much nicer paint job on the new machines. Do you have any others that you could post? Did you do the x and y power feeds as well?
 

kd4gij

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#13
I would of replaced the lousy lock screws and made my own mounting hardware. I don't like the way they mounted it.
Here is what I would of used.

1526521616674.png
 

Scott(GA)

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#14
Much nicer paint job on the new machines. Do you have any others that you could post? Did you do the x and y power feeds as well?
My machine is a dark grey.

I don't have any other pictures of the Cream colored machine.

I do have the X-Axis & Y-Axis Power Feeds as well.

I have installed the X but not the Y. Once I get the Z-Axis squared away, I'll look into installing the Y.

Here's a video of my exercising the X-Axis unit.

Best regards,

Scott
 

Scott(GA)

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#15
Back on May 11th I shared my discussion with JET Technical Support regarding the bracket for the JET Mill's Z-Axis Powerfeed Limit Switch.

That was a Friday. That following Monday, being aware of what often happens to newly initiated work over a weekend, I sent a gentle reminder email to Mary, my Technical Support contact.

Mary copied me on an email to another JET employee where she asked him to let me know the status of the Limit Switch Bracket.

I received no further communication from JET last week.

This past Monday I followed up with another email to Mary. She again copied me on another email to the same guy as the previous week. A few minutes later I got an email from that gentleman asking for shipping address information. I immediately provided that information.




20180525-01.jpg

20180525-02.jpg

I've been gone the past few days so I was hoping to find a delivery when I returned last evening but no...

However, late this afternoon, UPS delivered a package containing the bracket hardware.

I fiddled with the hardware for a while trying to make it look like the pictures that I had been sent from JET Technical Support back on the 11th. The pictures were certainly helpful but were slightly out of focus which, coupled with the black on black of the parts, made it difficult for me see exactly what was going on.

The real problem was that I didn't immediately see the two threaded holes in the end of the rectangular part with the two slots. With that piece of the puzzle missing, I thought maybe a part was missing from the box.

Then I saw the holes. Hmmm... what size are they?




20180525-03.jpg

20180525-04.jpg

I went down to the basement of my house and rummaged around in one of my "smaller fasteners" 5x5 drawer organizers. A couple of 1/2-inch #10-24 screws were just what I needed for the bracket.

I went out to the shop and positioned the assembled bracket on the side of the JET Mill. It looked like it should do the trick!

I hope to make some progress on mounting the Z-Axis Limit Switch assembly this weekend.

I will be posting dimensions of the bracket parts in the near future.


Scott
 
Last edited:

Buffalo21

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#16
When I put power feeds on the Jet JVM 836 and the 1940 round colum Bridgeport, I found the limit tracks to be very flimsy, so I attached them to a piece of aluminum angle, then bolted the angle to the milling machine, then made the limit switch brackets out of pieces of 1/4” steel plate, welded in the correct position, then bolted to the mills. 27492E81-1E58-47EC-A21A-3D9DBBF1BA8E.jpeg 44D968F2-F7D7-452E-B15D-115532D392BE.jpeg 32A13B46-B660-4B48-A2E9-F0DF313E4528.jpeg
 

PT Doc

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#17
Back on May 11th I shared my discussion with JET Technical Support regarding the bracket for the JET Mill's Z-Axis Powerfeed Limit Switch.

That was a Friday. That following Monday, being aware of what often happens to newly initiated work over a weekend, I sent a gentle reminder email to Mary, my Technical Support contact.

Mary copied me on an email to another JET employee where she asked him to let me know the status of the Limit Switch Bracket.

I received no further communication from JET last week.

This past Monday I followed up with another email to Mary. She again copied me on another email to the same guy as the previous week. A few minutes later I got an email from that gentleman asking for shipping address information. I immediately provided that information.




View attachment 268259

View attachment 268260

I've been gone the past few days so I was hoping to find a delivery when I returned last evening but no...

However, late this afternoon, UPS delivered a package containing the bracket hardware.

I fiddled with the hardware for a while trying to make it look like the pictures that I had been sent from JET Technical Support back on the 11th. The pictures were certainly helpful but were slightly out of focus which, coupled with the black on black of the parts, made it difficult for me see exactly what was going on.

The real problem was that I didn't immediately see the two threaded holes in the end of the rectangular part with the two slots. With that piece of the puzzle missing, I thought maybe a part was missing from the box.

Then I saw the holes. Hmmm... what size are they?




View attachment 268261

View attachment 268262

I went down to the basement of my house and rummaged around in one of my "smaller fasteners" 5x5 drawer organizers. A couple of 1/2-inch #10-24 screws were just what I needed for the bracket.

I went out to the shop and positioned the assembled bracket on the side of the JET Mill. It looked like it should do the trick!

I hope to make some progress on mounting the Z-Axis Limit Switch assembly this weekend.

I will be posting dimensions of the bracket parts in the near future.


Scott
Interesting that they didn’t supply all of the bracket pieces when you bought it from them. Keep us posted.
 

Scott(GA)

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#18
When I put power feeds on the Jet JVM 836 and the 1940 round colum Bridgeport, I found the limit tracks to be very flimsy, so I attached them to a piece of aluminum angle, then bolted the angle to the milling machine, then made the limit switch brackets out of pieces of 1/4” steel plate, welded in the correct position, then bolted to the mills.
Buffalo21,

That was nice work. Thanks for sharing!

Best regards,

Scott
 

Scott(GA)

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#19
Interesting that they didn’t supply all of the bracket pieces when you bought it from them. Keep us posted.

PT Doc,

I'm pretty sure the JET Powerfeeds are made by a Taiwanese company. I saw a YouTube video of an unboxing of this company's product and the boxes and packing were identical to the JET packaging.

I suspect this is much like a job my son had a few summers ago. He was working in a warehouse for a company that sold Air Conditioning Units for Semi Trucks. One time he told me about taking boxes of a product from China and putting the local company's label onto the box so that it covered the Chinese label. Then those boxes were shipped out to customers. My son and I referred to that process as "Value Adding".

I think JET employs the "Value Adding" process to their Powerfeed boxes. Ha!

To be fair, probably not that many people purchase the JET Powerfeed for a JET Mill. It could be for any Milling Machine. To add the JET-specific brackets wouldn't probably be that attractive to most customers.

Best regards,

Scott
 

Buffalo21

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#20
I have a Jet JVM 836, I wanted a knee power feed, Jet did not offer one, but Wilton had at that time a mill, identical to the Jet, that had a knee power feed. So I called HWM and asked if it would fit the Jet, they said, yep bolts right on, so I ordered it. Welp, it did not bolt right on, so I again called HWM, I told them the issues, their comment was classic, “ you own machine tools, make it fit”, then I heard a click as the line went dead. So I made it fit. None of the Jet power feeds I bought X, Y and Z, came with mounting brackets, just a basic kit, so I bought the next set for the Bridgeport from ENCO.
 

Scott(GA)

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#21
Z-Axis Bracket Dimensions 01.jpg

First of 2 sketches of JET Z-Axis Limit Switch bracket assembly.
 

Scott(GA)

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#22
Z-Axis Bracket Dimensions 02.jpg

Second of 2 sketches of Z-Axis Limit Switch Bracket Assembly.
 

Scott(GA)

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#23
A couple of weeks ago I started the process of mounting the JET Milling Machine's Z-Axis Powerfeed's Limit Switch Bracket.




20180528-01.jpg

There isn't a lot of space between the One Shot Lubrication plumbing and the upper Z-Axis lock. I positioned the Bracket and used a transfer punch to locate the center of the upper mounting hole.




20180528-02.jpg

20180528-03.jpg


20180528-04.jpg

I used a center drill to give the #4 drill bit a chance to start in the correct position. I used a small machinist square to ensure I was drilling the hole perpendicular to the side of the Mill. The blue tape was wrapped around the drill bit to give me a reference for the depth of the hole.

The #4 bit was the correct bit for a 1/4"-20 tapped hole with a 60% thread depth.




20180528-05.jpg


20180528-06.jpg


20180528-07.jpg


I used a 1/4-20 Taper Tap; followed by a Plug Tap and then a Bottoming Tap to prepare the hole to receive the upper machine bolt.



Continued in the nest post...
 

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Scott(GA)

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#24
Continued...


20180528-11.jpg


20180528-12.jpg

The hole was finished. This is only the second time I've tapped a hole for a bolt. I have to admit I was a bit concerned about doing this on my JET Mill. Time to see if I did it right.


20180528-13.jpg

I screwed a 1/4"-20 machine bolt into the hole... Looks like it worked!



20180528-14.jpg

I mounted the bracket using this upper hole to allow me to locate the center of the bottom hole.




20180528-15.jpg

Once again, a transfer punch was used to locate the center of the hole.



20180528-16.jpg



20180528-17.jpg

The bottom hole was prepared as the upper was. I was pleased to find that everything lined up and the base of the Bracket assembly was mounted to the Mill.


Continued in next post...
 

Scott(GA)

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#25
Continued...



20180528-21.jpg


20180528-22.jpg

The first part of the Bracket assembly was mounted to the Mill. As the pictures show, there wasn't a lot of clearance between the plumbing & the locking bolt.

This was all I had time for on that day a couple of weeks ago. I finally returned to the remainder of the installation a couple of days ago.
 

Scott(GA)

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#26
on June 12th I had enough time available to continue working on the JET Milling Machine's Z-Axis Powerfeed Limit Switch installation.



20180612-01.jpg

The Limit Switch Stops live in two pieces of aluminum channel.




20180612-02.jpg

20180612-03.jpg

The aluminum channel is held together with a bracket and 4 screws, washers & nuts.



20180612-04.jpg

With the aluminum channel assembled, I now combined the components of the Limit Switch Bracket. I then held the aluminum channel in various positions on the side of the Milling Machine's pedestal until I felt comfortable that I'd found a satisfactory operating location.




20180612-05.jpg

Using the upper standoff bracket as a guide, I used a transfer punch to locate the center of the aluminum channel's upper fastener.



20180612-06.jpg

Using a #22 drill bit, I drilled and tapped the hole for a #10-24 screw.




20180612-07.jpg


I tested it with a screw and all seemed to be well.


Continued in the next post...
 

Scott(GA)

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#27
Continued...



20180612-11.jpg

I mounted the aluminum channel to the Milling Machine using the top screw hole.



20180612-12.jpg

I used the transfer punch again to locate the bottom hole. I drilled and tapped the bottom hole as I had done the upper.





20180612-13.jpg

I mounted the aluminum channel by screwing the remaining fastener into bottom hole. I then located the stops at the upper and lower range of the Z-Axis.



20180612-14.jpg

This pretty well completes the Z-Axis Powerfeed installation. All that remains is to drill a 5mm hole through the Z-Axis Powerfeed shaft (white arrow points to the location) and drive in a pin.

...I have to get some metric drill bits.


Scott
 

PT Doc

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#28
Great photos. Should be very helpful for someone else in the future.
 

Scott(GA)

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#29
About a week ago I was working on the JET Mill's Z-Axis Powerfeed. At that time I had completed the installation of the Limit Switch Bracket.
The two tasks that remained were the drilling of a 5mm hole into the shaft of the Powerfeed followed by inserting a spring pin into the hole.

I procured a set of metric drill bits earlier this week. Today I thought I had time to finish this project.




20180623-01.jpg

The 5mm hole needs to be drilled where the white arrow is pointing.




20180623-02.jpg

20180623-03.jpg

I was concerned about my ability to drill a hole freehand through the coupler. I thought it would be better to do this on the JET Mill and then use a hand drill to finish the job on the shaft. I was playing around with how to set this up when I heard a small voice whispering in my ear...

"Is it possible", the voice said, "that drilling through the coupler without it being on a shaft will gall the internal threads?"

This did seem like a reasonable concern and I could fix it (I thought) by inserting a bolt into the coupler during the drilling process.

Without thinking about it too much, I grabbed the coupler and went back to the house basement where my hardware cabinets are. I had some 3/4" bolts and some 1" bolts. The coupler fell somewhere in between. The largest metric bolt I had was 14mm - much to small.

Off to the local Hardware Store. The Hardware Store had 7/8"-9 bolts and that barely started to thread onto the coupler and then stopped. The largest metric bolt they had was 16mm. I was leaning towards this being a metric thread at this point and I was guessing at a size of 22mm.

A Tractor Supply store was close by and they tend to carry larger hardware but I didn't know if they were going to have metric in larger sizes. They had 20mm but no 22mm bolts.




20180623-04.jpg

20180623-05.jpg


I returned home and did what I should have done before I went on that wild goose chase. I measured the shaft's threads.

I got a surprise.

The metric thread gauges didn't really match. 2.0 pitch was close but didn't quite match.

SAE 12 matched exactly! I measured across the shaft's threads with a calipers and came up with .853"

7/8"-12?
22mm with not quite 2.0?

Two questions:

What thread am I dealing with here?

Do I need to be concerned about damaging the threads if I drill through the coupler without something threaded through the coupler?


Scott
 

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#30
Reach in with a Dremel to deburr......
 
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