Jet Milling Machine JVM-840-PF - Riser Block

[Jim_Z]

I have been working on a 1980 vintage Jet JVM-840 milling machine for a while. I cleaned it all up, replaced all the bearings in the spindle and quill, and removed the power feed unit ( too heavy and restrictive of X travel). A Teco FM50 VFD should handle the 3 phase motor OK. I have come to the realization that the Z axis clearance between the table and quill is a little short for some of the fixtures that I plan to use on this mill.

The joint between the column and the turret on the machine is just under 8" in diameter. I am thinking that i could use a piece of 8" round bar about 6" long to get the extra clearance needed. Facing the ends flat and parallel. Drill three holes on an approximate 6" bolt circle for some long studs to connect the pillar and the turrent and I should be ready to go. I am wondering about what material to use for the riser block. I have found pieces of CRS 1018 and AL 6061 on ebay that could work. Obviously the AL is less expensive to ship. What are the thoughts of the collective on this.

Jim_Z

20160927_151416

• Jim_Z
• Mar 25, 2017

20170302_134543

• Jim_Z
• Mar 25, 2017
• 1

 

[Bob Korves]

Steel or cast iron would be the best choices. Make sure you will be able to get close enough to the work with a tool in a collet with a retracted quill and the riser block installed. You will be increasing the maximum Z axis capacity, but you will also be increasing the minimum Z axis capacity by the thickness of the riser block. Just looking at the photo, you might be OK for most work. Do not factor extending the quill in being able to reach your parts. That reduces rigidity of the setup considerably. That mill is pretty light already and needs all the rigidity it can get, don't compromise it.

edit: Welcome to Hobby-Machinist!

 

[Jim_Z]

I called around and found a 8" Round of Hot Rolled C1144 about 6" long for a C note in the area. That should do the job. Also found that a friend has an older 16" lathe that should be capable of machining the riser faces. The job is a little to big for my 10" Logan.

 

[tweinke]

Keep us posted with your progress!

 

[Silverbullet]

Doubleboost on YouTube has the same mill he added 9" to his. He seems to have no problems , he added length to the knee lifting rod to if I remember . Ck his out he tells how in one video. Turn volume up he's British and gets a bit of accent on there. Fun to watch

 

[Jim_Z]

Doubleboost on YouTube has the same mill he added 9" to his. He seems to have no problems , he added length to the knee lifting rod to if I remember . Ck his out he tells how in one video. Turn volume up he's British and gets a bit of accent on there. Fun to watch

Thanks Silver,
I will look for that video.

Jim_Z

 

[Grandpop]

I have an MSC clone of that 8 x 36 machine, same 1980's vintage. I started on a 5" high riser that has 8' 4130 rounds at the bottom and top. . What makes it different is a dovetailed slide in between the rounds that will allow some 14" of front / back travel. I have the rounds rough turned, but then I had to pack up my shop while garage addition was being built, have not gotten back to project to finish it yet.

From all of the calculations I did, it looked like 5" was going to work best for the vise, rotary table, and basic indexing work. Would still be able to reach the table with quill all the way down.

With all the time I have into roughing the dovetails, maybe I should have just made a plain riser, but the thought of that Bport like front/back travel was too hard to resist.

 

[Silverbullet]

Hey Grandpop , your close , I'm twelve miles from Philly on rt 70 . Are you going to use a rack or just threaded rod like a cross slide? Or I guess just push or pull. You have me thinking now , I have a enco that size and type. Would be nice to add the extra movement I'd be thinking how much I can move it . With a larger diameter say fifteen inches , safely six inches forward or back . Even slot one half to swivel the head sideways. Shoot we keep going we can add the nod.
If I can ever get out of friggin pain ill get some things done. One thing for sure ill be visiting some local scrap dealers for some materials. Angle iron for welding should be cheaper there then fazzios . I'm going to need a bunch heavy, light , and flat stock also. While there ill be looking for some rounds in the three to four inch thick range . After all the turning ill be able to surface grind them to tighter specs. Brains on now no sleep tonite.

 

[Grandpop]

I have been to Marlton before, about an hour away. I do like Fazzio's, but I go to the Delaware store. Was just there last week for 2 x 1 x 1/8 aluminum angle to make a poor mans circular saw track guide. 10' was about $10, couldn't find it cheaper anywhere.

I am visiting my 89 yr young dad in Fl right now, so don't have the exact dimensions of the riser in my head. My slide will just be pushed by hand. It will have a straight gib that the set screws will push on to lock it. I plan on giving it .005 clearance total so it should slide. The slide has dovetails on the top side and lower side, it is 2 x 7 x 14. You only engage the rounds about 6", so should be able to either move upper mount back 6" (I was hoping to be able to use the 90 degree milling head that way) or extend out to go past front edge of the table. My biggest limitation with the mill is not being able to reach the front of the part I am milling, so should fix that.

I thought about the nod, but just too much work to make it, and would loose the front/back travel. Also wasafraid it would not be rigid enough.

 

[Silverbullet]

I have been to Marlton before, about an hour away. I do like Fazzio's, but I go to the Delaware store. Was just there last week for 2 x 1 x 1/8 aluminum angle to make a poor mans circular saw track guide. 10' was about $10, couldn't find it cheaper anywhere.

I am visiting my 89 yr young dad in Fl right now, so don't have the exact dimensions of the riser in my head. My slide will just be pushed by hand. It will have a straight gib that the set screws will push on to lock it. I plan on giving it .005 clearance total so it should slide. The slide has dovetails on the top side and lower side, it is 2 x 7 x 14. You only engage the rounds about 6", so should be able to either move upper mount back 6" (I was hoping to be able to use the 90 degree milling head that way) or extend out to go past front edge of the table. My biggest limitation with the mill is not being able to reach the front of the part I am milling, so should fix that.

I thought about the nod, but just too much work to make it, and would loose the front/back travel. Also wasafraid it would not be rigid enough.

Yea that nodd would be tuff unless we make the whole head tilt at the riser. Nah to wimpy. So ill stick to a larger two piece riser with slots to turn and the dovetail , it may not need v dovetails slots and box tails may work easier. Really only need dovetails on ways which are used ALOT . I'd be more inclined of square ways and use brass lining to lock and slide. With the tee slot it can't fall out any more then with dovetails. I do admit they look great . But lots of the strongest mills use flat ways. Oh well that's a long way down my rode from now.
I haven't been to fazzios since they built up the building. Sent a friend to pick up some angle iron a few years ago but I'm planning on it. There and cooks machine, haven't seen Tom or boots in thirty years. I dealt with him through three different locations one was store the other a show place with a stage for performers. At one time I went weekly , sold an atlas shaper with stand for under a hundred bucks to him . Boy I wish I kept it legs and all.
Hind sight is blind sight. If I get the shop set up and you need any help I'm here. You can use my surface grinder if you need one or welding , I won't ask for money from fellow members but a couple bucks for electric if YA can if not no worries. I'm crippled up but I have many customers for MOWERS and such. They always try me first for needed items. I go the extra mile when I fix items to sell. I've only ever had one or two complaints , they weren't my fault the new owners used old fuel contaminated and stale. I take pride in what I do . Good luck on your build , hope you can get back to it soon.