Steve's Toys

Overview
Carriage drilling is adding a drill chuck to the tool post and use it in lieu of the tail-stock.
I have never been real happy with using the tail-stock for drilling small holes (< 1/4″). This is mainly due to the mass and weight of the tail-stock which can easily overwhelm smaller drills. With the addition of the Solid-Block Compound Replacement mod some new capabilities are now possible:

1. Precision alignment and recall of cutting tool offsets.
2. More precise drilling and reaming of holes in the work-piece.
3. Small holes are now easier to drill and ream.
4. The carriage power feed may be used for a precise feed rate.
5. Precise hole depth control using the DRO and/or the Electronic Leadscrew Stop Switch is now easier to achieve.

Requirements
While the following requirements may not be absolutely required they are highly recommended.

• A DRO is essential to use this function.
• The Solid-Block Compound Replacement mod is HIGHLY recommended. Else, you will be constantly fiddling with the compound to keep the spindle-drill chuck alignment true.

Considerations
The following items are shown as a starting point for implementing carriage drilling.

• Of paramount importance is to indicate the drill chuck center-line to the spindle center-line both fore, aft and vertically. The more precisely this is done the more accurate your setup will be.
• Large drills (> 1/2″) are not recommended due to carriage and cross-slide rigidity.
• Spot drills should be used in lieu of center drills for better accuracy.
• Short drills (machine screw/stubby drills) work best for accuracy due to drill flexing of longer drills.

Final Thoughts
I’m very pleased with the carriage drilling mod. Small holes are now a real pleasure to drill, ream and tap without the worry of breaking a tool.

(Click image to enlarge. Hit the browser back button to return)

Overview
This is another creature-comfort mod that I felt was necessary as I dislike hot chips being thrown on me and on the floor.  Obviously the hardest part of this project is a way to hold the chip shield and let it travel with the carriage. There are many ways to design a chip shield, this is just one.

Fabrication
Fab and assembly is pretty straight forward for this mod and no special tools are required.
Parts list:
(1) 2′ x 2′ x .080 aluminum plate
(1) 12″ x 3/8″ steel rod
(1) 7″ x 1/4″ brass pipe
(2) 1/4 EMT conduit clamps or ?
(2) 1/4-20 screws/washers/spacers to mount the pipe.
(2) 10-32 screws/washers/spacers/clamps/nuts to mount the rod.

Notes:
1) The spacers for the rod were fabricated from 5/8″ aluminum bar and were 3/4″ long. Your lengths may vary depending how you mount the pipe on the carriage.
2) When drilling the bottom hole for the pipe clamp be advised that the wall is pretty thin and there is an oil reservoir in that gearbox you will most likely drill into. Let the oil drain out and rinse the case with oil to remove any chips and use either silicone or LocTite on the screw when you install it to prevent leaks. Another possibility is to bond the 1/4″ thick spacer to the gearbox housing and tap the spacer.
3) The cross slide wood spacer is needed to take up the space between the chip shield and the cross slide hand wheel housing. A piece of 1x (3/4″) lumber works well for this part.

Picture Gallery
(click on an image to enlarge, hit the back button to return)

Overview
While I was in the mood for modifying the lathe I added a Variable Frequency Drive (VFD) to it so I could vary the speed of the spindle without having to stop the lathe to change speeds.

This mod was essentially straight forward since a direct replacement motor was available from Leeson that would just bolt up in place of the old one. A word of advice, this motor varies GREATLY in price ($300 – $2,000) so it pays to shop around.

The other required major component was an inverter to provide the 3-phase variable speed drive for the motor. I chose the TECO-Westinghouse L510 . This inverter has dozens of parameters that can be programmed to control how the motor performance can be customized to your specific setup condition(s). Which is a really nice feature.

Installation
Changing the Motor – requires removing the chip guard in order to gain access to the motor mounting bolts. Also, a suitable 3-jaw puller (3″) is required to remove the motor pulley which is pressed on. When putting the motor pulley on the new motor use a series of 8mm bolts/washer to pull the pulley back on the shaft.
Caution: Don’t beat the pulley on with a hammer as it’s possible to damage the motor.

Control Wiring – I elected not to try and use the existing electrical controls in the electrical box on the back of the lathe as the method of control is quite different using a VFD. The way I did this was to only use the wiring for the push-button controls on the front of the lathe which terminate at a terminal board in the electrical box. After wringing out the controls wiring with an ohm meter I found I could use the existing wiring and lathe operating controls without any modifications at all. See the wiring diagram for details.

VFD Control Box – A suitable enclosure was needed to house the inverter and associated electrical controls. I chose a Hammond steel electrical enclosure based primarily on the inverter dimensions and the size of the other electrical components. The main components beside the inverter include DIN Rail mounted heavy duty (30 amp) AC contactor circuit breakers and a 12vdc transformer. A 30 amp EMI filter is bolted directly to the enclosure. The whole installation is pretty straight-forward. I also added a 5″ muffin fan to keep the inverter cool as it can generate some heat depending on how hard the motor is being used. This fan is setup to run at half speed when the lathe is not running and full speed (3500 rpm) when the lathe is running. Also, converting from single (1) phase to three (3) phase power is not 100% efficient. See the wiring diagram for details of how the whole system is wired.

Inverter Settings – These are the settings I used.

Test Cuts
So far I’ve taken test cuts up to .250″ diameter with absolutely no pain or strain on the VFD or ELS. Here are the parameters I used for that cut:
2″ 12L14 steel bar, CNMG 432 insert, 700 RPM, .010 feed rate.
Note: My lathe uses a solid block in place of the compound slide which greatly stiffens the tool post. So this heavy a cut may or may not be possible using a compound.
Bottom line; the VFD and ELS are more than up to the job with room to spare. Very Cool!

Summary
This project was a fun and informative learning experience and I would do it again no question. Coupled with the Electronic Leadscrew (ELS) the Variable Frequency Drive (VFD) these two (2) mods have transformed the G0750G lathe into a very versatile and user friendly machine. I’m VERY pleased with the results.

Credits
Many thanks and appreciation go to James Clough for inspiring me to get off my butt and get started on this project that I’ve been putting off. His series of YouTube videos were very helpful and informative.

Picture Gallery
(click on an image to enlarge, hit the back button to return)

Overview
This is a project I’ve been wanting to do for a long time. Effectively, the timing gears are replaced with electronics that read the RPM of the spindle and synchronizes it to a stepper motor or servo that drives the Leadscrew which drives the carriage where the work is done. On most hobby lathes there is a set of gears (see pix #1 in the gallery) that must be changed to a specific set of gears depending on what feed speed or threading TPI (turns per inch) that is required for the job. Needless to say this gets to be a MAJOR pain even if the lathe has a gearbox to help.

The Designer
Thanks to James Clough (Clough42.com) who spent the time necessary to develop the hardware and software to accomplish this task. This was no simple undertaking and my hat is off to him for his effort and the expense required to get this done. He realized that a number of people would want to replicate what he did, so he put together a kit consisting of a control panel and a daughter pc board, that mounts on on a Texas Instruments micro controller board. These items would have been a real problem for most users to get sourced and assembled. He also produced a very comprehensive series of videos detailing his design and implementation of this project which is immensely helpful. Many kudos James, you are the man.

Design Decisions
My implementation is slightly different than what James did as my lathe is a little bigger (2hp). In my mind this requires a bigger stepper/servo motor than he used. I found out early-on that trying to find out how much horse power was required to run the drive system on my lathe was not going to happen. I did a lot of reading and Googling to no avail. I even called Grizzly tech assistance and they didn’t have a clue. So, what to do. I decided to try using a motor with 1/4th the horse power rating of the main spindle motor and hope that would be enough. I settled on a Teknic ClearPath servo motor CPM-SDSK-3446P-RLN. This servo is rated at 1/2hp continuous and ~1hp intermittently. So far it has proven to be more than adequate for the job.

Installation
Encoder – The encoder installation was, for the most part, pretty straight-forward. One exception was the spindle gear. The spindle on this lathe is 52mm and finding a GT2 gear that would fit it wasn’t going to happen. So, I bought a pair of 100 tooth pulleys off eBay and machined out the center of one of them which wasn’t too bad after I found out these type pulleys are actually an assembly of a ring and a hub. Turns out the ring was almost the right diameter so not much machining was necessary.
Motor – Mounting the servo was easy as the old gear banjo fitting was ready made for the purpose. All you need is a couple of modified 1/2-13 5/8 t-nuts and a plate to mount the servo. I chose 5mm HTD pulleys/belt as I felt the 3mm hardware might be a little light.
Electronics – The micro controller is mounted in a die-cast aluminum box and is magnetically attached to the lathe’s electrical box. Quick-disconnect plugs were added for easy removal.
Control Panel – I used the same die-cast box recommended by James to contain the control panel. I made a small bracket that attached to the back of the box and added a magnet which is attached to the top of the spindle gearbox . The nice thing about the magnet is you can adjust it to obtaining the best viewing angle.
Stop Switch – The one addition I made to this project was to add a stop switch to the carriage. When turning to a shoulder this is a real benefit. All it requires is a micro switch (NO) that is movable in relation to the carriage and a small relay (NC) in the electronics box to interrupt the servo Ena- line. This switch works VERY well and will stop within a few thousandths every time. The stopping accuracy is somewhat governed by the leadscrew speed and depth of cut.
Warning! The stop switch CAN NOT be used for normal toward-the-chuck threading as the synchronization between the spindle and leadscrew will be lost when the motor stops. However, this is not a problem if you thread away-from-the-chuck as I do. Which, completely eliminates the pucker factor.

Settings
Program Code Settings
These are the settings I used in the configuration.h file
// Steps and microsteps
#define STEPPER_MICROSTEPS 3
#define STEPPER_RESOLUTION 800
// Step, direction and enable pins are normally active-high
#define INVERT_STEP_PIN true
//#define INVERT_DIRECTION_PIN true
//#define INVERT_ENABLE_PIN true
#define INVERT_ALARM_PIN true
// Enable servo alarm feedback
#define USE_ALARM_PIN
Gearbox Settings – I have to admit this took a while to figure out because of the multitude of setting possibilities that exist, but perseverance paid off. The following settings work out perfectly without having to use the STEPPER_MICROSTEPS_FEED and STEPPER_RESOLUTION_FEED variables in the program.
Turning: A D N T
Threading: B D 4 V

Conclusions
I’m more than pleased with the way this project turned out. Listed below are some of the high spots I found:
– No gear changing required.
– Able to change the carriage feed rate without stopping the lathe.
– Both SAE and Metric threading instantly available.
– Extra spindle power realized from not having to drive the leadscrew from the main motor.

Picture Gallery
(click image to enlarge, hit browser back button to return )

Description
This tool is to provide a way to easily use a dial/test indicator without attaching it via a magnetic base or using the tool post. It can be moved around as it just sits on the lathe’s bed ways.

Bottom Plate
Consists of a flat steel bar (1/2″ x 3″ x 18″) sized to lay across the ways. The flat bar must be sized to be heavy and long enough to be stable when the indicator is moved. Note that the flat bar must be flat so it doesn’t rock when placed on the ways.

Dial Indicator Assembly
Base – 2″ round steel bar stock. Has two (2) small neodymium magnets (1/2″) recessed into the bottom to keep it from being pushed around by the dial indicator.
Vertical Rod – Size to suit your dial indicator clamp (~12mm)
Horizontal Rod – Size to suit your dial indicator clamp (~10mm)

In the image below the indicator is being used to dial-in a piece of bar stock on the 4-jaw chuck.

This is a tool post indicator mount designed to firmly hold a test indicator. Prior to this I was using a NOGA magnetic mount and it was real fussy to get setup. With this setup it is much more stable and can be left attached to the tool post if desired..
The holder was built from existing junk-box parts that were on hand. The only machining required depends on what you have and your setup. Mine was as follows:
1) drill and tap the bottom of the vertical rod (14mm) for a 3/8-16 thread and insert a piece of threaded rod for mounting to the MultFix QCTP.
2) Machine the indicator rod to fit the indicator holder (5/16 – 1/4).
3) Shorten a 3/8-16 socket head cap screw to plug the hole in the MultiFix QCTP if the vertical rod is removed.

This modification replaces the compound slide with a solid cast-iron block. The purpose of this is to make the cutting tool MUCH more stable. The compound slide has looseness and limits the lathe performance. Below is the build steps that are required.

Block dimensions are as follows;
Material = Gray Cast Iron
Dimensions = 4.8″w x 5.25″d x @.5″ h
Screws = 3/8-16 x 1.5″ SHCS
Weight = 13.25 Lbs.

A drawing for the block can be found here.

The block was designed to use either my Aloris BXA QCTP or a MultiFix QCTP which allows full access to all tools and holders in inventory.