Stuart engineering Lathe

[coopertje]

Dear All,

Since I am new on this site let me introduce myself for a moment. My name is Jeroen, I am 38 years old, I am from Holland and have an electronic background. Mechanics always had my interest, so in 2007 I bought my first machines and started to build a 17cc one cylinder IC engine. Since then I have added a lot of machines and tools, I spend the last 2 years in getting my things organized and converted some machines to CNC (mach3). Further I did a project with some friends on using hobby CNC machines to make a IC engine, the OTTO from Jan Ridders. The article series has been published in model-engineering magazines here in Holland. In March this year I started a big project, a 1to8 scale Stanley steamer. I am making some progress on this one, but not as much as I would like, my hobby time is limited. Well, enough about me.

Before starting the Stuart Lathe story I would like to compliment all of you for putting so much effort in this site! It has been a real source of information and inspiration for me. I know better how much time it takes to take photos during machining. Most of the times you are having fun machining and then in the end you realize that you forgot to take pictures. As said before, my hobby time is limited, so this will be a long tread. But that's why its called a hobby if you ask me. Since I learn and enjoy a lot from this site I feel its my obligation to share some project with you and let you learn from my mistakes and bloopers (and trust me, I am an expert in this!).

Well, here we go. I could not longer resist to purchase the casting kit for the Stuart engineering lathe. Below whats in the box:

I never worked with castings before, so where to start ??? I choose the machine bed, that part did not looked too complicated. First step is convert all the dimensions to millimeters, I really cannot work with inches! Next step is to face mill all sides of the casting to get it square and somehow near the correct dimensions.

1st the top is faced

Then the bottom

Next will be the sides of the machine bed, I hope to post this soon!

Regards Jeroen

 

[gbritnell]

Hi Jeroen, and welcome to the site. As you have found there is a lot of information available here and the members are some of the nicest and most helpful you will find.
I have seen the pictures of the Stuart lathe but have never seen one finished. Yours will be a first. I have built many Stuart kits and they are very nice castings and quite compete kits.
gbritnell

 

[tel]

Welcome Jeroen.

 

[swilliams]

Welcome, I'll enjoy watching your project develop

regards Steve

 

[coopertje]

Thank you for your welcome gentlemen. And I agree, the Stuart kits are not cheap but you get nice quality back for it. The castings look very nice and the material machines very nice.

I found a little time and worked on the sides of the machine bed.

Started with checking my vise with a micrometer to see if it was still straight on the machine. Even though this machine will not produce any chips at all I would like it to be straight and accurate. When the vise was within 0.01mm straight I placed the machine bed in it. There are 3 runs to do for each side. First is to bring the smallest width to its final dimension. In the same cut I want to end with a thickness of 4mm for the upper part of the bed (the part where the carriage will run and that will get a 60 degree chamber later on). I did this cut with a 20mm end mill.

After I took a 6mm end mill to rework the pocket on the side. The depth is set to just have the casting marks/structure to be removed and for the rest I just followed the contour of the pocket in the casting.

Last is to reduce the width of the carriage guide. The final width will be 40mm, height 4mm. Since I just needed to take of a little more then 1mm I used the same 6mm end mill for this cut.

Next machining will be the T-shape in the middle of the bed and bringing the bottom and sides of the part to the final dimension. It will have a nice symmetric shape around the side pocket of 4mm.

The bed is placed in the vise with top facing up. Then determined the exact middle to make the basic shape of the T (8mm deep). I used a 6mm mill for this, the final width is 8mm. So I have 1mm left on each side to clean up the cutting surface, or make some re-adjustments in the set-up in case I made a mistake somewhere.

With the basic shape formed, I toke a T-cutter, 16mm diameter and 4mm height. I found this operation a little scary, never did a T-cut before. Normally I am quite careful with cutting depth etc, with this operation you have only one choice and is to have the mill completely in the material. I set the machine to a slow 200 rpm and carefully tried the 1st part by hand. I was surprised how well it went, so I finished the cut on the autofeed (40mm/min). The fear was ungrounded, it all worked out well and I am happy with the result.
I took the 20mm end mill again and finished the outer ends of the bed.

Afterwards flipped the part in the vice and brought the bottom to its final dimension.

Thats all for now.

 

[coopertje]

Tonight I worked on the headstock base and tailstock foot. There is not so much work on these parts, they need to be faced on top and bottom sides and get some holes so they can be fixed to the machine bed.

On the picture below the top of the headstock base is machined. I did not machine the bottom side yet, first I wanted to machine the upper side of the tailstock foot. When this job is done I can put the bed on the parts and check and measure how much material I should take away from the bottom.

The tailstock foot is irregular shaped and therefore difficult to setup in the machine. I tried it straight in the machine vise and it felt quite rigid. Even though my feeling told me this is NOT a good setup, I guessed if I take a light cut it should not be a problem.

I still had the big mill (40mm diameter) in the toolholder, started the machine and tried carefully by manual feed to see and feel what would happen. The mill “eated” the material away nicely and there was no shatter at all. Scary, but not bad…… I started the autofeed and while milling the upper surface I was watching the process holding my breath. The most critical part was the end, the point where the mill is already trough the middle and you just have 2 pieces of rest material left on the outer edges (I hope you are able to understand my English!). At this point the mill does not cut in a linear way but starts to hit the material. Also this critical part went without any problem until all material was removed. I was relieved and satisfied, thought just let the mill run over completely so I get equal machining marks over the surface (completely useless, they will be hidden by the machine bed!). I turned around to grab the vacuum cleaner (do not like to have castingchips over my machines) and at that moment I heard a terrible sound…… th_wtf1 th_confused0052 :redface2: :wall: Even though the mill was already completely trough the material somehow it grabbed the tailstock foot, bended it and eventual broke it into 5 separate parts. After 5 minutes of calling myself all kinds of things that I will not write down here (why do I always continue while my feeling tells me it will not work…) When I got myself together again I took a bottle of 248 lock-tide and started to glue the pieces back together. Maybe with some filing, plaster and sanding I could save the tailstock foot. It came out terrible and was completely out of shape and even worse…twisted. After thinking over several plans to rescue the part I surrendered and admitted to myself I screwed-up. I should have known better, my feeling warned me but I continued and now I have to accept the result. I will consider this learning money and up to now this has been much less than a educational course in metal working ;D The good thing of a Stuart kit is that you can order separate spares, and thats what I will do.

Here is the result after gluing the bits together….

While waiting for the spare to arrive I have enough time to think on a good setup. Probably I will make a dedicated jig to machine this part. Ideas are welcome!

Next will be to fix the head- and tailstock to the bed.

CU Jeroen

 

[gbritnell]

Hi Jeroen,
After looking at your photo of the broken piece I think I figured out what might have happened. The part where you clamped in the vise has draft (a casting angle) on it and it's a rough cast surface so you didn't have much clamping area even though the vise was tight. Before you cut the next one, clamp it horizontally and clean up that small edge then when you stand it upright put a piece of paper between the casting and the vise jaw. This will give some friction between the vise and the casting and help prevent it from slipping.
gbritnell

 

[coopertje]

Hi Gbritnell,

Thanks for the idea! I am not sure if I will follow this way, I would like to have the same casting structure all around the foot. Looks better for me. Also I got afraid to machine the part standing upright in the vice. I am sure that using a much smaller mill (6mm for example) and take several cuts would help a lot. I was thinking to machine the new part horizontal in the vise and try to clamp it from the side (near the to be machined surface, then I will have minimum moment/force on the casting during machining). The difficulty with this set-up will be to get top and bottom planes parallel and to have sufficient "grip" on the casing sides. The tip of putting paper will surely help also in this set-up. Thanks for that, I will use it!

BR Jeroen

 

[mklotz]

My take on it is that that big slot in the middle says, "run a bolt through me and clamp this part to a sacrificial plate shimmed such that the top and bottom (of the foot) are vertical". Then use a side cutting endmill to finish the top and bottom, cutting into the plate in order to cut across the entire top and bottom.

 

[coopertje]

Thanks Marv. This feels good to me, to have the casting horizontally in the vise. The set-up with the bold trough the slot will do. I will add some material so support the sides of the casting, with such a setup it cannot go anywhere.

I will try to get over the fact to sacrifice a piece of aluminum, I am Dutch remember.... :

BR Jeroen

 

[hobby]

You wouldn't have to sacrifice aluminum, you can make good fixtures using wood.

Or

If you have a spin jig, then an unusual arbor can be made to bolt through the middle opening, then you could mill the top, spin it 180* and do the bottom.

That would ensure the top and bottom would be parrallel, with eachother.

 

[steamer]

Yes a piece of hardwood sure.....As George has said, it's hard to start with castings due to draft. The vice just doesn't like hanging on to tapered parts. Paper may certainly work here!

When I started my launch engine, it had lots of draft to contend with...I got around it by using a piece of sheet lead used for roof flashing. When I clamped it in the vice with the lead liners, it conformed to the irregular surfaces and the roughness of the casting and really hung on to the part long enough to get a good flat surface on one side....it got easier from there.

I understand that most European countrys REALLY frown on any use of lead, so a piece of soft copper or soft aluminum flashing might work. Just don't tighten too hard!.....it's a small part


Saying that...
Marv's comment about bolting it down is a very good one.It may be a lot less stress on the part...I'd be torn as to which way to go unless I could see the part first hand.

Additionally, you may want to use a smaller cutter and take light cuts until you have two sides flat and square to each other.


Hang in there, it's a process...and the best way to learn is to do.....if you do this long enough...this event will happen....ask me how I know this.... ;D


Best of luck to you and keep the pictures coming!


Dave

 

[swilliams]

Sorry to hear about the part going bad Jeroen, but as Steamer says "hang in there". You've got some good advise, I'm sure you'll get there soon enough

 

[coopertje]

Thank you all for your effort to supply ideas and (mental) support! They are very helpful, I never thought of using wood or lead! It brought light in the dark, I am sure I will find a suitable set-up so I do not damage the new part again. Never realised that the draft or rough casting shape affected the clamping. So logical when you think of it afterwards......

I have ordered the spare today, hope it will not take too long to have it in hand.

I decided to make some changes to the original drawings for the lathe. One will be the tailstock. In the plans they mention a treaded bar going straight through the hand wheel (http://www.stuartmodels.com/inprod_det.cfm/section/casting/mod_id/64). I do not like it, I never saw a lathe in real live having this construction. Second change will be the cross slide. According to the plans the hand wheel is fixed to the cross slide, meaning it will move in and out together with the cross slide. I will change it to a spindle and nut principle so the hand wheel position is fixed to the saddle of the lathe instead. Think I will put the lathe in CAD to have the correct dimensions for the parts. By doing so I can also change the dimensions to metric and pre-fit the parts in software..... more easy to adjust and correct in software then on a machined part!

 

[coopertje]

Today I did some work on the head- and tailstock.

I started with securely clamping the tailstock in the vise and used a 3D indicator to find the middle of the piece.

Took a cut on both sides such that the remaining width in the middle was 8mm

Then I reduced the height to 3.9mm. The bed is 4mm so in this way I am sure that the tailstock is fixed when it is tightened!
As last operation on the tailstock (at least for today) I drilled a hole of 4mm for the tailstock clamp.

For the headstock I used the same procedure:

The tailstock clamp consists of a square plate with a treaded pin and a nut. I chose to use a 4mm pin with M4. From the square rod, included in the material kit, I made the following.

Put the material horizontally in the vise and face mill the edge until the saw cutting marks are gone.

Mark the middle of the square and put the material straight in the vice. After center drilling, drill a hole of 4mm, 3mm deep.
I used a saw to cut off a piece of 2mm thickness.

The 4mm rod is made of silver-steel (can be any other type of steel). I put the M4 tread and after cut it to length.

Then the 2 parts are joined by silver-solder.

Finished clamping feature for the tailstock.

Since things went well and I had some time left I decided to drill the mounting holes to fix the headstock base to the bed. The headstock base is mounted with screws through the bed and fixed in the headstock. In other words, the machine bed is clamped between the headstock and headstock base.
I put the headstock in the correct position to the bed and fixed it with clamps. This assembly is placed upside down in the vise. I marked the drill positions and center drilled them. Then drill trough with a 2.5mm drill (pre-drill size for M3). Be careful to not drill too deep, the holes in the headstock are meant to be "blind holes". I stopped drilling approximately 2mm before the point where the drill would go completely through. In this same setup I drilled the holes in the bed to 3mm.

After tapping the headstock with M3 the headstock base can be mounted. Below the status at this moment. In the background my "in progress" 1906 Stanley Steamer.

Regards Jeroen

 

[coopertje]

Guess its not my weekend! Yesterday my Heidenhain TNC121 broke down. Its a position controller on my big mill, very nice device. Today I disassembled the unit and replace the capacitors and resoldered the components. In most cases this help with a piece of electronics of 30 years old. Unfortunately it did not help, I was afraid of this already. Well, at least I can use it as DRO unit, lets see what the future will find on the second hand market.

After struggling with the controller I decided to mount the gear-rack on the Stuart (bad idea when your mind is not clear!!).

I started with making a nice 3mm radius on the gear-rack with a radius mill.

Then mounted the rack on the side of the machine bed and clamped both parts together. Calibrated the first drilling (there will be 4 in total) and made a center mark with a center drill. Then I start drilling the 4 holes completely trough with a 1.5mm drill, the gear-rack will get a M2 treading. While drilling the last hole I looked at the bed and though.....how will I get a screw in here scratch.gif ......and only after 30 seconds it hit........ *club* :wall: I was drilling on the wrong side of the bed!!! Definitely not paying attention on my work!

Swapped the Gear to the other side and clamped it. The good thing was that the center drillings where already there...

Next step was to remove the gear-rack and drill the holes in the bed to 2mm.

Took the bed out of the vise and glued small pieces of 1.5mm wire in the wrong drilled holes.

It can be machined after 30 minutes, so enough time to make the M2 tread in the gear-rack. This is quite a delicate job, these small sizes break very easily....(still need to make a piece of equipment to help in this operation). I did it very carefully and slowly and luckily it went well. Time to fit it on the bed.

At least the fit was very nice, no gaps around. Last machining for today was to machine the glued in pieces of wire.

After painting it will not be visible that anything went wrong here, so if you guys do not tell anybody nobody will know!

Jeroen

 

[swilliams]

Looks good Jeroen

At this rate you'll finish everything else before the new leg turns up

 

[coopertje]

Thanks Steve. I am not so sure, I hope to receive the part next week. Too bad I will be abroad for work almost the complete week, so no progress next week.

Today I was able to spend some time in the shop and drill the holes in the head and tailstock. I started with measuring the center of the hole to be drilled. Since I do not have a flat table yet, I use the machine vise instead. Although it is a little small, it works very well and perfectly flat!

Then placed the bed in the vice and checked if it was parallel to the spindle with a dial indicator. Found the middle and center drilled it very slightly. Then check with a magnifying glass if it was in the correct position. At this stage it is easy to make corrections if required. Next I drilled the headstock true with 4mm and in the same drilling made a center drill in the headstock.

I drilled the hole in the headstock in the following steps, 4mm, 8mm, 12mm and 16mm which is the desired final diameter. My machine did not have enough height, so I had to remove the tailstock from the bed and move the headstock down. Luckily the setup was and remained straight, so this did not cause any issue in re-referencing the setup.

With a successful drill in the headstock, it was time to attack the tailstock. The plan is to drill 4mm, 5.9mm and then ream to 6mm:

The backside of the tailstock needs a pocket 8mm in diameter and 6mm deep. I used an end mill to drill this pocket.

That's all for today, next will be to make the internal parts for the tailstock. I am looking forward to make then, finally something that moves on this lathe.

CU Jeroen

 

[coopertje]

There is a little progress in the lathe. I am putting it into a CAD system to have a good feeling about dimensions (I am changing them from imperial to metric). It is not finished yet but below is what I have up to now:

Since I did not like the original construction of the tailstock I changed it.

In the exploded view you see from left to right:

- Tool holder, 6mm outer diameter with a 3mm reamed boring inside
- Treaded bush, 5mm outer diameter, M3 internal
- Tailstock casting
- Spindle
- Handwheel
- Handwheel handle

I made the toolholder from 2 separate pieces because M3 needs a predrill of 2.5mm and I only have a conical reamer of 3mm that needs to go completely trough. Gluing in the treaded bush after reaming the toolholder to 3mm solves this issue.

I started making a 6mm diameter rod to 26mm length. Then center drilled it, drill 2.5mm, drill 2.9mm and finally reamed it to 3mm.

Then drilled a 5mm hole, 10mm deep using an end mill. In here the treaded bush will be glued later on.

The 5mm bush was cut to length of 10mm and after center drilling drilled with 2.5mm. Put the M3 tap in the tailstock and made the first part of the internal tread. When it is stable enough (or deep enough) I removed it from the tailstock and finished it by hand.

Since I am a lazy machinist I made the spindle from 2 pieces. First is a piece of 3mm drill rod with M3 on one side.

I took a piece of 8mm drill rod and cut a groove of 3mm wide. When mounted in the tailstock a set screw in this groove will keep the spindle in place.

When the grove was finished I drilled a 2.9 mm hole and cut the piece to a length of 6mm. Last operation was to ream the internal boring to 3mm.

Below the separate parts before and after gluing. I use Locktite 648, after 30-45 minutes it is impossible to get the pieces separated!

As you can see below the hole in the tailstock is above the center of the casting. I accepted this because the visual line up with the headstock is ok. Later I will put the tailstock in the rotary table and make it centric around the drilling.

Next I drilled 2 holes from the top of the tailstock and tapped them with M3.

Time to fit the parts together and test the movement!

All the parts fit well, and the toolholder moves in and out nice and smooth....

Finally I made a groove in the toolholder with a 2mm end mill. I took 2 cuts of 0.5mm.

Some days ago the new leg for the lathe arrived. I have the setup already in mind (thank you all for the tips!) and hope to make some chips on this part soon.

Thanks for watching, CU Jeroen

 

[user 4756]

Hi Jeroen,

Thank you for sharing your project...and your mishaps! :-\

I am only new to this hobby and your (and others) obvious professionalism tends to overwhelm me so that I am afraid to make a start. :bow:

The fact that you can get it 'wrong' too gives me great incentive to push on through and not worry about it. As Bogs says, you don't know unless you try.

It is good to hear your comments on the Stuart castings as there are many criticisms; maybe they have an 'export quality'.

Please keep posting as this model has fascinated me and 'her indoors' for a while.

Andy