ERL-1340 Cross Slide Lock for DRO Equipped Lathes

[mksj]

Often when doing tight tolerance work one needs to lock the cross slide to get consistent diameters along the length of the cut. My ERL-1340 was fairly tight when new, but over time I did noticed slight shifts in the cross slide position from my original setting. I am using glass scales, and I do not have access to the gib cross slide lock under the scale,. Using spacers between the carriage and DRO scale was not a good option because of the carriage design. In the past I fabricated a cross slide lock on the headstock side of the carriage, and opted fopr this approach for the RERL-1340. This one is made out of 25 mm wide aluminum bar stock with a lower cutout step so the face to carriage distance is about 0.01". The lock is 1" bronze rod with a 7/8-14 (UNF) thread which I cut to the shoulder, there are four 1/4-28 threaded holes at 90 degree intervals for the locking bar. All that is needed is about a 10 degree movement for full carriage lock. The lock mounts to the follow-rest mounting holes, and is easily removed if needed.

Cutting the 7/8-14 thread with a lay down threading insert at 350 RPM.

Installed.

 

[azonin]

I need to make a new lock on my 1440, since the DRO scale is blocking it.

 

[rafprecision]

Initially installed a DRO PROs on my 1340-GT, with no regard for cross slide "lock down". Eventually got this corrected with some aluminum flat bar stock and a "milled" socket head bolt ...

 

[rafprecision]

While I'm here, some more pics....

Thanks to MKSJ for the help...

Home made tachometer...

VFD control box. Many thanks to MKSJ for the inspiration...

Last, but not least, homemade "fog buster" ! Did get a little "carried away" with acetone however ...

 

[mksj]

Hi Mitch,

I considered putting spacer blocks under the scale, but on the ERL-1340 the slim line scale sits in a notch in the carriage and if it is pushed out any further it hits the oil fill plug/carriage. Might have been able to do something different with a magnetic scale, but the lever on the other side is very easy to use and I do not need to search for another allen key or wrench.
Mark

 

[Cadillac]

Here's what I came up with for the cross slide lock with the scale blocking it. I had the cross slide apart for a bunch of modifications like oil ports and grooves and I new I had to come up with something. I decided to go from the top drilling a hole inline with the original horizontal hole but vertical. Then tapped that hole to a m6x1.0 I believe. Next I took a pushrod from a engine which has balls welded to the ends of a rod that fit perfect in the hole. I measured end to end to get my max distance then tig welded back together. I then took a full thread bolt chuck in the lathe and bored out a hole for a another pushrod cut to length. Here's a pic of the parts and cross slide to help explain.

If not clear the rod with the balls on both ends goes in where the stock set screw is then just put the set screw in flush. Then the bolt with the ball at the end goes in the top right hole in pic which is inline with setscrew hole. When the bolt gets tightened it translates the motion 90* to the rod which in return locks the gibb.
I haven't finished my mods yet with the cross slide but have tested just by pulling on the top slide once locked and it doesn't budge. My plan is to cut the head off the bolt and make a small knob to engage lock. After thinking about the configuration more and more I ended up making a rod with a brass end on it. I plan on matching the gibb angle on the end instead of the ball which I presume is hardened. Which I haven't fitted yet but have the rod made. Now I will have a lock on the cross slide which was usable since day one. The oiling was another issue for me. Oil port above the sliding surface and gib and they hope it migrates down the dovetail to the flat surface all up and down each side. Then pick a side of the gib and do the same. No good in my book. I put new ports with grooves on dovetails and flats of all sliding surfaces. Should work real good haven't done final assembly yet. I'll have a write on it when done.

 

[ddickey]

Often when doing tight tolerance work one needs to lock the cross slide to get consistent diameters along the length of the cut. My ERL-1340 was fairly tight when new, but over time I did noticed slight shifts in the cross slide position from my original setting. I am using glass scales, and I do not have access to the gib cross slide lock under the scale,. Using spacers between the carriage and DRO scale was not a good option because of the carriage design. In the past I fabricated a cross slide lock on the headstock side of the carriage, and opted fopr this approach for the RERL-1340. This one is made out of 25 mm wide aluminum bar stock with a lower cutout step so the face to carriage distance is about 0.01". The lock is 1" bronze rod with a 7/8-14 (UNF) thread which I cut to the shoulder, there are four 1/4-28 threaded holes at 90 degree intervals for the locking bar. All that is needed is about a 10 degree movement for full carriage lock. The lock mounts to the follow-rest mounting holes, and is easily removed if needed.

So the bronze rod just screws/pushes against the side of the cross slide? Seems like a design flaw by Sun Master, no?
What will you do if you need to use the steady rest?

 

[mksj]

I used this setup for years on my 1340GT and worked very well, the issue of access to the cross slide lock on lathes with a DRO scale is common problem to most manual lathes. The bronze rod pushes against the cross slide, it is softer than the cast iron so there is no wear. The alternative would be to use a magnetic scale in a different arrangement, but in almost all cases getting to the gib lock would still be difficult with the chip shield. I think it was Jim who put a magnetic scale under the cross slide, I would probably just mount the magnetic tape directly to the cross slide and put the reader head on the back side of the carriage (the new reader tape/head are very small, no chip shield is needed). Pushing the scale out with spacers eats up some of the tailstock travel.

I like Cadillac's approach, but would need to pull off the cross slide. With the lock I am using, if you need to use the steady rest the lock on the headstock side has no effect, if the follow rest, the lock unbolts and you just bolt on the steady rest. I can always tweak the gibs to increase the tension if needed, but we are talking a creep w/o the lock of a few ten thousandths.

 

[ddickey]

Did you install the slides or did the factory install them?

 

[mksj]

They do not come with factory installed DRO's., but the US distributor may offer installation. QMT provided the ES-12B DRO and scales, I installed them with my own mounting brackets.

Easson 12B DRO lathe install with glass and SRA M-DRO magnetic scales

Just completed a Easson 12B DRO install on my ERL-1340, I opted for the stock glass scales for the X and Z0 axis for cost reasons, but wanted to use the 3rd input on the Easson 12B DRO head. When I previously looked into the use of magnetic scales a few years ago with the Easson DRO's I was told...

www.hobby-machinist.com

If I new that the SRA magnetic scales were available and worked with the ES-12B, I might have just mounted the magnetic tape to the top of the cross slide and put the reader head on the back of the carriage with no chip cover.