Benchtest.Com - Workshop - South Bend 405 lathe bench

The SB 405 gets a bench
September 22, 2011
Back in 2006 when I got my South Bend 405, it didn't come with a bench. When I got done stripping it down, cleaning, painting and reassembling it, I decided to temporarily mount it on the end of my layout table. This is a large 4' X 8' table made from 4"X4", 2"X4", and 3/4" plywood with a piece of laminate topping the plywood. Pretty sturdy, but all wood and subject to movement when the weather changes. I leveled out the lathe the best I could under the circumstances, but it doesn't stay put very well. Notice that I said I temporarily mounted it to the layout table. That was in 2006 and it's now late summer of 2011. Not so temporary, I suppose.

A while back I came across an orphaned Rivet 918 lathe - again without the bench. Now I had two lathes needing benches. I've been keeping my eyes open for benches of all sorts that I could adapt to either one lathe or the other. However, I haven't had much success in getting one to follow me home.

Some time ago, plans for a copy of the post WWII South Bend workshop lathe bench were made available on the Yahoo southbendlathe group. I took a look at them and liked what I saw. From what I understand, South Bend sold the lathe bench as a kit to be assembled by the owner. It's designed using 2"X2"X1/8" angle steel with a butcher block top. The butcher block top wasn't my first choice. First choice would be a metal top or metal chip tray, but I've looked for a chip tray that would take the 3 1/2' lathe bed and be deep enough that the motor and counter shaft would fit for quite a while without success. Finding some quarter inch steel plate in the size I needed (48" X 24") is not inexpensive and it seems to go up weekly. It almost makes me wish I bought the plate a few years ago when it was only expensive. Now it's outrageously expensive.

Lately I have been fighting a taper when I turn longer pieces of stock. Each time I try to dial the lathe in, the weather changes and that causes the table to warp and that results in the lathe bed twisting. I'd finally had enough so I went to my second choice for a bench top; butcher block. The plus side is that it is better than the current plywood top. The thin stringers of maple that make up the butcher block means that humidity will produce less overall movement and warpage in the stacked strips than it would in a single board or plywood top. The down side is that wood still isn't as stable as metal.

I started looking for angle steel and for butcher block tops. After pricing all the places that advertised that they sold tops for work benches, I happened across Lumber Liquidators who sell butcher block counter tops. I could purchase one of their 8 foot by 25 inch by 1.5" thick counters for little more than a 24" X 48" work table top from Grizzly or the like. Once I cut the counter top in half, I'd have two tops for about the price of one.

I set up a cleat to guide my circular saw for making two 4 foot tops from the 8 foot one. I had considered using the table saw, but the 8 foot length was a bit more than I could handle by myself. The Williamsburg Butcher Block Co. branded maple top looks to be machine made from fairly thin, an inch or so, strips. The strips on the front and rear ends of the butcher block were joined using a locking joint - Z shaped - instead of simply butting them together. These joints were very precisely done but again they appear to have been only used on the edges. The majority of the rest of the joints were butted together pretty well, though there were some spaces between boards that you wouldn't find in a hand laid up butcher block. Certainly good enough for a lathe bench, but not fine furniture quality. I was a little disappointed that the surface of the butcher block wasn't flatter. I'm thinking that maybe the maple strips were a bit high in moisture when the block was sent through the plainer and then subsequently dried out and warped. The end result was that when running my hand over the surface, it was uneven. I was able to flatten it a bit by attacking it with my belt sander. After a few passes of 80 grit, I switched to an orbital sander and 220 grit. I worked with the 220 grit until it was smooth and a bit flatter. I suppose that I could remove the top at some point and get it planed again.

The last step was choosing a finish. I had been thinking of using polyurethane, but after doing some research, I decided on tung oil. From what I had read, the tung oil would soak into the wood and provide a deeper layer of protection than using the poly which sits on the surface. Over the course of a week, I put 3 coats on each surface; top, bottom and sides. Each coat was buffed out with the fleece side of an old sweatshirt. Even my wife commented on how nice the finish came out. That is high praise indeed for a tool table.

For the steel frame, I wanted to make some changes to the South Bend plans. First, since the butcher block top was 25 5/8 inches deep, I needed to change that dimension on the frame to accommodate the width. My lathe, counter shaft and motor will fit in about 22.5", but 25"+ gives a little extra room. I also wanted the stubby lathe feet to bolt through the butcher block and into the metal frame to make things a bit more rigid. The distance between the feet bolt holes on my SB405 are 33 3/8", so that would be the width of the frame. Last, I wanted to use leveling feet on the bottom pf each leg, so I would need to attach some 3/8" flat steel with threaded holes to the bottom of each leg. This is another case where a MIG welder would have been a better choice than my Oxy-Acetylene setup, but I haven't found one in my desired price range. The brazing ended up working fine and this bench should be able to support a lot more weight than I will ever put on it.

Lots of holes needed to be drilled in the angle steel to assemble the frame. Some holes were done on the mill with the digital read out, some were done on the drill press and the lower shelf stringers were done by clamping the 1" X 1" angle steel in place and drilling with a hand drill. I chose this method because I wanted to be able to measure and adjust each 2 leg pair to be as square as I could get them. With the use of a machinist's square, carpenter's square, a couple of scales and a measuring tape, I got each boxed in side square within a 32nd of an inch. Once shelf bracket was clamped in place, I drilled two quarter inch holes for each connection. I ended up with a frame that was square and pretty rigid. I still will probably add some diagonal braces to make the frame more rigid, but I'll save that project for another day.

The top was attached to the frame with 1 1/4" length square drive decking screws with all of the butcher block holes pre-drilled to prevent splitting. I attached the bed to the table, then drilled one hole for the counter shaft foot so I could check the alignment of the lathe to counter shaft before I drilled any holes in the wrong place. After spinning up the lathe for a few test runs to make sure that the serpentine belt ran centered on the step pulleys, I drilled the remaining holes for the motor and counter shaft assembly.

With the bench done, I started dismantling the lathe. A couple years ago, I read a post on the southbendlathe group that discussed the fact that the bed feet for the workshop lathes were not matched in height. Since one of the reasons for this project was to end up with a level and untwisted lathe bed, I wanted to make sure that the lathe ways were parallel with the frame and butcher block top. I had also noticed that when I assembled the lathe in 2006, I had the feet swapped. The foot with the holes is supposed to be under the headstock to allow you to route the switch wiring through it. I was pretty sure that I assembled the lathe exactly as I had taken it apart, but that doesn't mean that the previous owner hadn't swapped the feet before me. No matter, I would assemble it correctly this time.

Once I had the feet off the bed, I cleaned them up and placed them on the surface plate so I could measure them. The one with the hole, the headstock foot, was about 0.008" shorter than the foot that goes under the tail stock.. I would match grind the feet on the surface grinder, but first I needed to check to see that the top section that bolts to the bed was flat. I blued up a surface plate and checked each foot top. Neither were particularly flat. I spent the remainder of the evening scraping each top flat. Once I had finished, the difference in height was only 0.005", but I would fix that on Saturday using the surface grinder.

I hadn't used the surface grinder in quite a while. I cleaned off the coating of oil that protected the magnetic chuck from rusting and then slid a straight edge over the surface to see if it needed a skim cut. It still was pretty flat. Good deal. I checked the coolant concentration and started up the coolant pump. I adjusted the stream of coolant and decided that I should probably pre-lube the ways. I squirted some way lube on all of the ways by using the manual feeds to move the X and Y axes. I was now ready to go. I fired up the hydraulic motor. It took a little time to bleed the air from the system and get movement from the cylinders, but after working the levers for a bit, the hydraulic feeds were working as they should. The final step before setting up to cut was to true the wheel. I selected a 7" x 1/2" 32A60-KVBE wheel that was already mounted and gave it a tap with the spindle wrench to make sure it rang. If it doesn't ring when lightly struck, break the wheel with a hammer and throw it out before it explodes and hurts someone. I trued the wheel with a single point diamond, then shut down the machine to setup the lathe feet for grinding.

I had marked the high point of the two feet with a marker and once the feet were held securely by the mag chuck, I brought the wheel down to touch the highest spot, then backed off 0.001". With the hydraulics on, but the spindle off, I swept the wheel across the feet using the hydraulic feeds to make sure that I had indeed set the wheel height to the tallest part of the feet. I really don't like surprises and trying to take a too heavy cut because I didn't set the height correctly was something I'd rather not experience.

With more than 0.005" to remove, I could have cut the feet a little closer on the mill, but I hadn't used the surface grinder but once all winter and it really needed a workout. It turned out that there was a dip in one of the feet that I hadn't noticed when I had them on the surface plate and I ended up taking almost 0.016" off of the highest point to get the feet matched, level and parallel. Grinding this much material took a while, but it was enjoyable to use the grinder after not using it for a long time.

Once I finished grinding and drying off the feet, I took them back to the surface plate and test indicator. There was now less than a thousandth of an inch difference between the heights of the feet.

I reinstalled the feet on the lathe bed and made sure the the foot with the hole was under the headstock this time. I leveled the bench using my Moore and Wright level. I mounted the lathe bed with 2 bolts through each foot and used the level to help me put the right amount of torque on each bolt to get the flat tops of the V ways level at both ends of the bed. After reading many accounts that the flats at the top of the ways are not machined true, I found this out for myself. I ended up using the 405's original saddle placed on the ways to level the bed. My 405 shows next to no wear on the bed ways or the V ways of the saddle. When the bed ways are blued and the saddle is placed on them, the blue pattern on the saddle ways is close to perfect with about 80% coverage, evenly distributed across all surfaces. With the level on top of the saddle, the bubble in the vial stays in the same position across the ways from the headstock to tail stock ends. With the level placed on the bed way flats at the top of each V, there is a pronounced movement in the bubble as the saddle is slid from end to end. It would have been really tough to level the bed without having good ways and a good saddle to use for reference.

When I first assembled the lathe, I had left the previous owner's wiring pretty much intact. This time, I would rewire the lathe to place the power cord back by the motor instead of coming out of the bottom of the switch. While I was working on the switch, I noticed that one of the brass contacts was about to break in half. I made up a new contact out of some spare brass stock. I'm happy to say that I caught this before the contact failed as a 1" piece of brass loose inside the switch could have made for some excitement if it happened to fall across the two legs of the 110 volt feed.

I placed a junction box next to the motor and carefully soldered all of the motor connections and neatly routed all of the wires. I added a couple receptacles for the work light and whatever else I might need to power. I was feeling rather pleased with my neat job when I discovered that I wasn't such a pro at wiring after all. I had wired the 4 motor wires with solid copper wire and forgot that the motor moves up and down when the belt is loosened to change speeds. Now the motor fought against the 4 solid wires when I tried to move it. Duh. Oh crap! That was enough for one night. Time for bed and I'll deal with my stupidity tomorrow.

After thinking about it for a while, I figured that I would wire between the junction box and motor with some very fine multi-strand silicone insulated wire that I had from my RC cars. This stuff is super flexible. I had some 14 gauge, orange and black pieces and color be damned, that's what I would use. I needed to disassemble and desolder all of the junction box wiring to tie in the new wire. Did I say that I hate doing things over again? Anyway, I routed the wires so that there was a small loop to allow the motor to move and re-soldered everything back together. I sure hate it when I screw up, but it was back together and I had forward and reverse, so all is well.

Now that the bed and motor were attached and the lathe was wired, I moved on to one of the reasons that I had started this project. I needed to scrape in the model B saddle I had added to the lathe to give it lateral and cross slide power feeds. I had added the newer saddle and apron a while ago, but had put off mating the saddle ways with the bed ways.

To check and see how much metal I needed to remove, I blued up the outside bed ways and set the saddle on the ways. I gave the saddle a tap to the left, then a tap to the right to transfer some blue from the bed to the saddle, then pulled the saddle off and inspected the print. The closest surface to the operator had some color, then next had none. The third face, actually two faces as it is split where the cross slide fits, had a little less blue than the front. The last surface, again actually two surfaces, farthest from the operator, had none. OK, not so good. I could see why the saddle didn't hold position very well. For the heck of it, I checked the original saddle again. All of the V surfaces had nice uniform blotches of color over their entire length.

The V ways on the bottom of the saddle are not very wide. This makes them harder to scrape. The #1 and #4 surfaces are a bit wider than the #2 and #3 and the #3 and #4 ways are split into two sets with the V ways separated by the area where the cross slide screw resides. To add a little more difficulty to the scraping job, the #4 position pair of ways has the casting boss for holding the rear plate that prevents the rear of the saddle from lifting. This is placed so that it interferes with the scraper. My 1" wide scraper blades could not reach past the obstruction, so I made a 3/16" wide scraper from a broken file to help me scrape this surface. Scraping with a converted file lasted a day before I was wishing for carbide. I had some 1/4" by 1" by 1/8" thick carbide tips, so I cut one in thirds and made a new scraper. I can't seem to get as nice of a finish with carbide as opposed to using a hardened steel scraper, but not having to sharpen the steel scraper every 5 minutes is a real plus. Sharpening the carbide scraper's end is done on a dedicated aluminum face plate coated with 1800 mesh diamond dust in oil. The sides of the scraper are sharpened on a flat glass plate coated with the same diamond dust in oil carrier. One sharpening will carry me through scraping the whole saddle once, as opposed to having to sharpen the steel scraper 5 or 6 times for the same surfaces.

Getting the 3 sections of V ways to show color when I placed the saddle on the blued bed ways didn't take long. Getting a good pattern on all 6 of the flat sections that make up the 3 V ways took much longer. Removing the Prussian blue and cleaning the ways with alcohol between each printing takes time when you are trying for a perfect print. One little fleck of steel stuck in the marking blue - or red - as I switched to red water based marking fluid as the scraping got closer to being finished - will ruin a print. It took a few weeks of evenings to finally get to where there was red being transferred evenly along all 6 of the flat surfaces that made up the 3 V ways. One of the hardest things of working with V ways is trying to set the saddle on the bed ways so that it doesn't touch or slide into position as you set it on the bed ways. With the blue on the bed ways, any place the saddle touches will pick up color and give you a false map of where to scrape. Another issue that I had was trying to evenly apply the color to the bed ways. On surface plates or wide flat ways, I use a 4" long 3/4" diameter short nap paint roller to apply the color. This works OK on the V ways until you need to thin out the color as the scraping gets more precise. It was hard to get an even thickness of color on the tiny V ways. I tried using felt as the applicator, then shop paper towels, then a gloved hand. Nothing worked all that great. I would either get the red on too thick or so thin that only the very highest of the high spots on the saddle ways would print. This is OK for accuracy, but since you are only scraping a few high spots per printing, it takes forever to make any progress. I reread the lathe section in Machine Tool Reconditioning by Edward Connelly, but I didn't see anything mentioned other than the roller used for inking print on a printing press or an ungloved palm of the hand. I have one of these brayers (print rollers), but it doesn't work for beans for me.

As long as I am talking about scraping, I'll pass along some of things I've learned over the past few years. There are things that I find are very hard to remember to do. First is to rough scrape all surfaces until there is good basic bearing. By this I mean that there is color being transferred to all of the flat sections and that each flat section has color across its whole surface. I have a tendency to want to start finish scraping too soon. This results in the job taking much longer than it should. Another thing I have to force myself to remember is to only move the item I'm scraping a short distance when trying to transfer color. Moving the saddle 1/8" to the left, then back 1/8", then removing it is enough to get a good print when finish scraping. Moving the saddle a greater distance only serves to blur the high spots. I can't tell you how many times I've pushed it a half inch there and back three or four times and then found that the color was transferred in stripes instead of small spots on the high points.

I finally finished up scraping the saddle. That is not really a true statement as one never really finishes scraping - you just stop. I finally stopped scraping is more accurate. Once you have thinned the marking fluid out to the point that there is just a thin haze and you still have color being transferred to all sections of each way, you probably have good contact between the parts. How much further you want to go depends on what you are trying to achieve, but I had more than enough spots of color per half inch to allow the saddle to run smoothly and truly on the bed ways. It must be another of my things to learn about scraping, but I have a hard time stopping. As the bearing gets better and better, I tend to think "One more pass and I'll call it finished." When I finish the next round, I say the same thing. This went on for a few nights until I took a print, it looked good, so I wiped off the color and stopped. It is somewhat of an anticlimactic situation. What? Nothing more to scrape?

Anyway, the next step was to try the apron on the saddle and see if I had lowered the saddle too far. This is more of an issue for the model A lathes with the quick change gearbox where is is difficult to move the gearbox and leadscrew down if the automatic apron worm drive is rubbing or pressing down on the leadscrew. I say that it's more difficult as there are more parts to shim, but the process is the same. If the worm drive is pressing on the lead screw, you need to shim the lead screw bearing blocks down by some amount. On the A models, you need to shim the bearing block on the tail stock end and shim the quick change box on the headstock end. I used pieces of feeler gauge until I found the proper amount, then cut shim stock to match the top side of the bearing blocks. By the way, I am using a matched saddle and apron and didn't try to mate the newer style apron with my older 405 saddle. Even though the 405 saddle is in pristine condition, the newer (later model) saddle is a good deal wider than the old one and the apron wouldn't swap easily between them.

I fitted the apron to the saddle and checked for binding between the lead screw and apron drive assembly. I had added 0.010" shims between each of the lead screw bearing blocks and bed when I had first installed the saddle. The lead screw was now running a little high compared to the worm drive. I added another 0.005" shim per side and that did the trick. The leadscrew was now centered in the worm drive. I cut some 0.015" shim stock to fit around the two screw holes in each leadscrew bearing block and replaced the feeler gauges with the shim stock.

The last thing to check on the saddle to bed fit was the gear to rack fit. I got lucky here. Due to the differences in the 405 and model A/B saddle and apron, the gear to rack fit was a bit tight. The scraping I had done had added a bit more clearance. That put the gear in pretty close to perfect alignment with the rack. Cranking the saddle along the ways was very smooth now. This was a good thing as the only adjustment for too tight a fit - in my situation - would be to skim cut the top side of the rack. I really didn't want to do this. If the rack to gear fit was too loose, the rack could be shimmed down. Either way, I got lucky.

Now that I had the apron and saddle fitted, the next step was to scrape the cross slide. I had already scraped in the compound slide a few months earlier when I needed to cut a very exacting 60° taper for a project. The cross slide fit actually felt pretty well as it was, but there was a bit of stick/slip when cranking the cross slide under the pressure of a heavy facing cut. The dovetail ways were worn pretty smooth and tended to stick together. To try and improve matters, I would scrape the bottom of the cross slide and leave the ways on the top of the saddle alone. I would scrape just enough to get decent bearing and leave some low spots to hold way oil. Last year I had fit bearings to the cross slide and compound slide screws to get rid of some of the backlash slop there. At some point, I would like to replace the cross slide screw and bronze screw nut as there is about 0.005" of play, but it's not real high on my list of priorities as it's easy enough to work around the bit of backlash. After inspection, I ended up replacing the thrust bearing on the outboard end of the cross slide screw. Years ago I had made up my own thrust bearings and thought that I had found races for them that were sufficiently hardened to not deform under the load from the highly hardened precision balls I used for the bearings. However, the feel of the cross slide had been deteriorating and when I checked the thrust bearings, I found that the balls had worn tracks in the races. Apparently the races weren't hard enough. I had some thrust bearings I had purchased from McMaster-Carr for another project that came with hardened races. The outside diameter was a bit larger than the thrust bearing I had made, so I needed to bore out the recesses in the micrometer dial and screw boss to fit the new bearing. Once the new bearing was installed, I was back to having a very smooth action while turning the cross slide screw.

With the cross slide back on the saddle, I leveled the lathe again. There is a little twist in the bed. I needed to crank the right rear bench leg adjuster down a bit to raise the rear bed way on the tail stock end to get the level to read right. I will need to set the table level again and remove this twist with shims under the lathe feet I took some pictures of how the bed leveled out and will refer to them again when I get ready to shim the bed using Rollie's Dad's Method to remove any bed twist. I will then turn a test bar to check for twist. I've done this a few times in the past and I agree with all those sage folks who say that turning a test bar is the best way to tell if the lathe is set up correctly.

Well that's about it for this installment. The next installment will cover setting up the lathe to remove any twist in the bed. Until then, happy chip making.

Here's the lathe before starting the most recent projects. The 405 has the later model A/B saddle and apron fitted, but not scraped in yet. The lathe chuck is a Bison 6". It's a nice heavy duty chuck.

Measurements for the SB 405 lathe bench.

Less than perfect joints on the Williamsburg Butcher Block Co. counter top.

Each joint has two bolts to minimize movement.

Frame is assembled and butcher block has had 3 coats of tung oil.

The bench frame gets a couple coats of paint to match the color of the lathe.

The butcher block is attached to the frame using backer board screws due to their holding power and nice square drive. Why aren't all wood screws fitted with square drive sockets like these?

Getting ready to remove the lathe bed feet.

Measuring the height of the lathe bed feet before scraping the tops and surface grinding the bottoms.

Scraping where the foot attaches to the lathe bed. A couple more scraping passes and we'll be ready to surface grind the bottom of the feet. This should enable the lathe to sit parallel with the bench top.

Rough scraping. Scraping in V ways takes a while.

A new scraper is made. The carbide tip is 1/4" wide and 1/8" thick. Just what I needed.

Finish scraping - near side ways.

Finish scraping - far side ways.

Leveling the longitudinal axis - near headstock.

Leveling the longitudinal axis - center.

Leveling the longitudinal axis - near tail stock. All three readings are pretty close.

Leveling across the bed - near tail stock.

Leveling across the bed - center.

Leveling across the bed - near headstock. We have a bit of twist here, but we'll deal with that by using Rollie's Dad's Method to remove any bed twist and cutting a test bar to check alignment.

Not much color showing on the first print.

Getting a better pattern here.

Pretty close to done.

Close-up of the previous print. The amount of marking color used on the top surface of the saddle that I printed from was pretty light, so there's probably half a ten-thousandth to two tenths between the areas with color and the areas with no color. There are some unmarked areas that are scraped a little deeper, but I'm pretty sure that using a thicker coat of marking compound to print from would probably color pretty much the whole way surface with red.

The cross slide gib was tricky to print as it is a very spindly piece of metal that bows due to the being scraped. I used a granite straight edge to push the gib into the color rolled on to a surface plate. In this shot, I had another 5 or so passes to go.

I replaced the cross slide screw outer thrust bearing. The one on the screw and the one at the lower right were made from scrap plastic and precision balls. The new blue one is from McMaster-Carr. After much use, the larger home made bearing was getting a little notchy due to not using hardened races. The smaller indside bearing was fine. The new bearing and hardened races make for a nice feel when turning the crank.

All back together and ready to be aligned

Close-up. While the import tool holder is of pretty good quality, that big "China" on the front sure looks tacky.

I needed a way to hold the lamp base and still allow me to position it. Some stacked oak, glued and pinned with some 1/4" drill rod worked out well.

Another shot of the lamp holder.