Model Engine Maker
Engines => Your Own Design => Topic started by: JonC on December 09, 2019, 04:32:02 PM
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Hi all,
I've moved this away from my introduction a while ago and have some progress to show, however I'm struggling with the file size limitation for uploading photos and videos.
Can anyone tell me what the get-around is please.
thanks
Jon
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Hello Jon,
I use the 'Coppermine' image hosting website set up by AdeV our system Admin and top computer wizz. It was set up to overcome the 'Photosuck-it' problem we had a while back. Have a look at this link, it tells you all you need to know.
http://www.modelenginemaker.com/index.php/topic,7249.0.html
Cheers
Mike
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I still use Microsoft Office Picture Manager to compress my pictures for the forum. The documents option works well. There are plenty of other compression programmes available.
I upload my videos to YouTube and then paste the link into my posts. The 'embed YouTube' button above does not always seems to work.
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Thanks for the replies guys, I'll take a look and see if I can sort.
To be honest I'm struggling with posting anything on here, I'm a total newby at this and not sure what I'm doing.
I'm sure I'll get the hang of it eventually.
jon
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does this work?
https://www.youtube.com/watch?v=HxWjaYZWrjo
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I can see that :ThumbsUp: Looks excellent :praise2:
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Good grief i hate when people record with the phone held vertically. makes me feel like im looking thru a key hole.
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Good grief i hate when people record with the phone held vertically. makes me feel like im looking thru a key hole.
Steve, I'll get used to it in time.
jon
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Would appreciate any thoughts on how to investment cast the DFV block. It's full of return angles and has the web across the top of the cylinder banks making it quite tricky.
At the moment I'm going down the avenue of splitting the block into six separate chunks that could be moulded in wax and then melted together for the full block. These would be -
Front
Left cylinder bank
Right cylinder bank
Bottom end
Rear
Web
I have printed these in 1/8th scale and have just printed the reverse mould for the right cylinder bank to see if it will work.
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Now that I have a 3D printer I am going to follow this thread daily! I have plans this winter to try casting Zamak in plaster molds using PLA prints as the pattern. This will get burned out prior to casting.
Gerrit
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Hi Gerritv,
sounds like were both on a learning curve this winter :shrug:
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Decided to start with a simpler part than the block to produce a wax, so I've been working on the Head. No idea if this will work but I've reversed printed the six faces and tongue and grooved them. Just need to put holes in to fill and vent and then give it a try.
Thinking that maybe I'll need to put some sealant around the gaps to stop the wax leaking out perhaps. Also guessed at plus 6% for shrinkage.
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Jon:
I made a silicone boot for my 3D printer using a mold process similar to yours', I used high temp silicone caulk to make the boot. The leakage through the joints between the mold parts is not that bad of a thing, it gives any trapped air a place to go.
How easy will you be able to clamp the mold parts together? I made mine to slot together in a sequence, my mold mostly worked. I got a usable boot out of it, but it's not pretty. I know that I need to redesign the mold before I make anymore.
Clamp your mold together and do a test shot, that will tell you what parts of the mold you need to fix. I'm guessing that you might need to change the tabs that align the mold parts, getting it clamped together might be a trick.
Don
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Thanks Don, there's hope yet.
I'm not sure how runny the wax is but I would think that it's more runny than silicone so I'm hoping that leakage is only slightly worse. If it's too bad then I'll try some rubber solution glue or something.
As you can see my mould sides slot together into a box so I'll just get some tight rubber bands around it to hold it all together.
Jon
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Hello Jon,
I am not sure whether my adventures in pattern making and lost wax casting will be of any interest to you.
Have a look at reply 25 onwards and decide for yourself, http://www.modelenginemaker.com/index.php/topic,7559.0.html
Any questions, just ask
Mike
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Hi Mike,
Yes thanks, I am following the Jupiter build and took some useful information from the manifolds you made including the investment casting people, very impressive work I might say.
I may still try the silicone mould method you employed but thought I would try this method first.
Jon
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Hi Jon,
I am very interested in your method of using 3D printing for lost wax castings. It is a completely different method to the one I used, so I am following along quietly in the background and learning from you.
I can see that 3D printing has many advantages over hand carved masters with the potential to eliminate several process steps towards the production of usable waxes. I am watching and learning from your experiments and experiences. One day, I may even invest in a 3D printer of my own.
Keep posting your progress
Mike
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shapeways can provide parts printed in wax,, they will also do the casting,, they also do metal printing.. they are pricey ..
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Mike, glad it's of interest to you. The mould scan easily be rescaled and reprinted as well however the post processing is quite laborious.
I hoping that if it works, it will allow multiple waxes to be produced without distorting or damage. My machining skills are nothing like yours so I'll need quite a few back up castings I'm sure.
tghs, thanks for the info, I'll look them up
Jon
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Jon,
I sometimes used a company called Sculpteo, they offer a similar service to Shapeways and appear to be marginally less expensive. Both firms specialise in commercial 3D printing in a wide variety of plastics and metal.
Both firms also offer a complete lost wax casing package. From your 3D model to the finished lost wax casting in your chosen metal. Unfortunately, they only offer a complete end to end lost wax casting package, they will not supply the printed waxes to a customer or accept a customers waxes.
Mike
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looks like shapeways has dropped the wax only option,, there should be other providers,, I have seen some vids using PLA in place of wax,, there are also some material options for home 3D printers..
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.... One day, I may even invest in a 3D printer of my own.
They have come down in price Mike. Surus' new one only cost £70 on fleabay. I expect its quality and capability to be reflected in the price but it is an investment in a learning process... And I already have my first printing order :noidea:
Jo
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Mine is a £120 Chinese Geeetech printer. It's been excellent.
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Jon,
I sometimes used a company called Sculpteo, they offer a similar service to Shapeways and appear to be marginally less expensive. Both firms specialise in commercial 3D printing in a wide variety of plastics and metal.
Both firms also offer a complete lost wax casing package. From your 3D model to the finished lost wax casting in your chosen metal. Unfortunately, they only offer a complete end to end lost wax casting package, they will not supply the printed waxes to a customer or accept a customers waxes.
Mike
Still getting used to posting
Mike, what about the Covent Garden jewellers you used? Are they still up for casting from customer waxes?
Although I would imagine that materials will be restricted from them, specially in a high grade aluminium
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Mike, what about the Covent Garden jewellers you used? Are they still up for casting from customer waxes?
Although I would imagine that materials will be restricted from them, specially in a high grade aluminium
Jon I have not checked recently but "Just Castings" is their name and that's what they do for a living. You send them your waxes and get the finished castings by return post (after you pay the invoice). If you have a small item and are prepared to wait a few extra days, they will add your waxes to other customer's waxes to save a little on the costs. If your item is large, or you are in a hurry, it may need a complete investment flask by itself. That will cost about £160 for a flask.
BTW you also need to pay for the amount of metal used. They are jewelers, so normally cast in precious metals. I have never bought aluminium by the gram before, fortunately it is a light weight metal, and not intrinsically valuable.
If you are in a hurry and get the wax to them by mid afternoon they will mount the wax and pour the invest the same day. The evening shift place the investment flaskin the burn out oven overnight and it will be at full temperature and ready to go early next morning. The hot flask is then placed on the vacuum caster and the freshly molten metal is drawn into the cavity. By mid morning the casting will have removed from the used investment, the runners sawn off , the casting cleaned and inspected and readied for the customer. Better than a 24 hour turn round. They cast in different metals every day of the week and are very good at what they do.
The aluminium they use, appears to be pure aluminium, not a high strength aluminium ally; so it is rather soft when it is delivered. I have not tried any heat treatment to precipitation harden the aluminium. It is therefore soft and gummy to machine and tapped holes have no great strength. HE30 T6 is is NOT
Hope this helps
Mike
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Thanks Mike, very helpful.
Going to order some red wax soon and see how it goes. Then if all is ok I'll decide where to go for the casting.
Jon
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Jon,
After you have injected the molten red wax and allowed it to solidify; use cold water to harden the wax before you attempt to remove it from the mould. The cold water will also lower the skin temperature of your hands and fingers, making them less likely to leave marks and finger prints on the wax.
Keep us posted with progess
Mike
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Mike,
How runny is the wax when hot? Is it like water or more viscous?
Also I saw that you heated it immersed in boiling water. Is it important not to get it above 100 deg ?
Jon
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Jon,
The wax takes a long time to fully melt (heat of fusion or something like that) so you need to be patient, stir it regularly to make sure it has all melted and there are no hard bits left. Take your time and don't rush things. Dont be tempted to directly heat the pan of wax, always use a double water boiler to stop the wax exceeding 100C. The wax is quite runny near 100C but stiffer at lower temperatures. I used a kitchen thermometer to ensure I had the wax temperature as near to 100C as possible. You need to be efficient and get the molten wax into the mould before the temperature drops and it thickens. As you have seen, I always use an injection syringe pump, I have never tried to pour it into a mould.
The wax also takes a long time to harden in thick sections.
Mike
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I used metal syringe as a poor mans wax injector and used casting wax,, attempts with other wax failed,, some waxes change in qualities if over heated,, just keep the syringe in the molten wax, pump the wax in and out before filling a mold.. pouring also failed..
https://www.ebay.com/itm/NEW-PREMIUM-GRADE-Ear-Syringe-Metal-6-oz-Stainless-Steel-A-QUALITY-GURANTEED/302518874648?hash=item466f87b218:g:QAEAAOSwR2RaAlfJ
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Thanks both for the information. I thought I would try the mould with some silicone that we use at work to measure unobtainable features. I re-printed the base of the mould with two 7mm holes to fit the nozzle on the gun. Unfortunately there was nothing like the volume I needed to fill the mould even with two cartridges but I am pleased with the result.
There is leakage around the joints of the mould creating flash and that is with the silicon with a viscosity of something like engine oil, so I think this will be worse when I use wax. I'm sure this can be easily removed but it may be worth trying to seal the joints in order to keep this to a minimum.
I'm also wondering if it would be better to include the inlet and exhaust ports in the mould? I was thinking that the valve detail in the head would be produced in the form of a cartridge of all four valves set into the head and this would therefore have some of the port detail on it and be easier to produce rather than machining on the head itself.
any thoughts would be appreciated
Anyway, wax next and then hopefully casting one to prove out the theory and check the shrinkage
Jon
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Just came across this via Hackaday, seems like a potential good way to smooth prints: https://www.thingiverse.com/thing:3666116
Gerrit
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Hi Gerritv,
Do you think this polisher would be useful for finishing small metal parts as well as PLA?
Mike
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Certainly, it is the same principle. I just thought it interesting as applied to PLA.
There are other tumbler builds shown on YouTube among other places.
Gerrit
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Thanks Gerrit, don't know why I haven't thought of this before. Tumbling is a great way to polish and smooth metal components so why not printed PLA with the right media?
I once visited a manufacturer of high end bicycle parts and they machined small four pot brake calipers from aluminium and then tumbled them in nut shells. The finish was unbelievable.
I think I'll investigate this because if the trial on casting the head works I've got the block (6 separate parts), cam carrier, cam cover, gear covers and crank case to do.
Jon
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just thought I would show the nose cone and front wheel rim I printed a while ago for the Tyrrell 003 that inspired me to produce the DFV.
The car and Jackie Stewart hold a special memory for me as a young boy with my dad who alas died when I was 13 :(
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for some reason the pictures always turn through 90 so trying again.
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Trying again
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Jon,
The problem with the rotation of pictures has to do with the way the data is "physically" (well, really electronically) stored. In any digital camera, the pixels are always stored in the same layout, regardless of camera orientation. For example, let's say the "normal" orientation for a camera is "landscape." The pixels are stored in a landscape orientation, one row after another. When the camera is rotated to "portrait" orientation, the pictures is *still* stored in landscape orientation - but it is marked with "metadata" that indicates that the pixels should be re-arranged to portrait orientation when shown. That works great, most of the time - the camera or computer re-orients the pixels according to the metadata without the user ever knowing it.
Unfortunately, when a picture is uploaded to certain sites - including many types of forum software - the metadata gets stripped out. As a result, the picture is shown based on the "physical" layout of the pixels, whether that is correct or not.
The solution is to run a program that rearranges the pixels to the correct orientation and stores them that way "physically" (electronically). This can be done manually with a photo-shop type program, but it is a pain. For my own use, I long ago wrote a small program that lets me re-orient and optionally re-size pictures for use in email and forums on a bulk basis - very quick and convenient.
I downloaded your picture, ran it through the program, and am uploading it again - voila!
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The DFV is certainly one of the better looking engines in F1. I built a model of Tyrrell P34, and then a friend gave me this coverall badge which was given to him by Jackie Stewart at one of the GP's at Mosport in Ontario in the 1970's. The cars from then are much more interesting than the crop from last 10-15 years.
Gerrit
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Awake,
That's a great explanation of why I'm struggling, thank you. I thought that saving to file and then rotating and saving in an image viewing file would sort it but I see why not now.
I assume that now I should just take pictures in landscape mode only?
Gerrit, yes those were the real days of innovation and shear bravery. The badge is iconic and even more special being given from the man himself.
Jon
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Gerrit, yes those were the real days of innovation and shear bravery. The badge is iconic and even more special being given from the man himself.
Jon
Yes. Those were the days when sex was safer but motor racing was bloody dangerous
Sadly, never to return
Mike
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:Lol:
True, and you could have a quick cigarette before climbing aboard.
jon
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Awake,
That's a great explanation of why I'm struggling, thank you. I thought that saving to file and then rotating and saving in an image viewing file would sort it but I see why not now.
I assume that now I should just take pictures in landscape mode only?
Glad it helped! Right, an image viewing file "rotates" the picture only by changing the metadata, not the actual organization of the pixels.
Certainly one option is only to take pictures in the native orientation of the device. Alternately, if you want, I'd be happy to send you the program that I've been using for years - contact me via private message. I would have uploaded it as an attachment to this post, but unfortunately, the zip file of the program is just a bit too large for the maximum size allowed for uploading to this forum.
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Thanks Andy,
I'll try the landscape option and see how it goes. Otherwise I'll be in touch via PM.
Jon
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A few update photos. I still have to get round to producing the waxes for the block and have been doing a lot of the other bits. Five speed Hewland FG400, suspension and printed a tyre master that I'm going to mould in rubber like the CV boots I've already done.
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Wow, with a different background these would look like photos of the real thing.
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Jon
This is very impressive work, are you using original drawings or the real thing for reference. Do you still intend to make castings available to buy?
Mike
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Jon,
It's unbelievable how frail those suspension arms look against the massive tyres. Pleased to see you back on the forum.
Mike
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Hello again chaps, yes now that COVID is slightly less a part of my life I have a little more time to post.
Gerrit, thanks for that, I do try to be as near as possible to the real thing in all aspects.
Mike, It's a bit of everything - some known dimensions but very few to be honest, some super imposing a 3D drawing over a picture and some that make sense because of the known dimensions. Word got around and I was invited over to Hewland Classic Gearboxes for a look around which was a great help. The suspension etc is from the Tamiya 1/12 Tyrrell 003 model.
Mike, nice to be back in touch again. Yes it all looks fragile to the wheel doesn't it. I actually had to check the wheel dimensions myself to make sure it was correct but it is, although they seemed to run bigger tyre sizes in the mid 70's compared to earlier and this is the larger. I think when the rest of the suspension is on with wing supports etc it will look more in proportion.
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Jon
This is very impressive work, are you using original drawings or the real thing for reference. Do you still intend to make castings available to buy?
Mike
Sorry Mike, missed the bit about casting. Yes absolutely, I have the moulds made for the block and the wax etc to try them out with. Just need the time to set it up give it a go.
Jon
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Hi all,
Knowing the huge amount of knowledge out there, I wonder if I could ask for some feedback on another version of the DFV I'm working on. As you will see it's a belt driven version that still stays true to the engines appearance but massively simplifies the gear train of the original. Again it's 1/4 scale and uses 6mm wide x 2.5mm pitch dual belts allowing for the cylinder stagger that has been increased from 0.2" to 0.236". Crank pulley would be 0.375" diameter and Cam pullies 0.75" diameter.
This is just an initial layout drawing so any thoughts about whether this looks viable would be appreciated.
I have looked at the Bouland engine which seems to work ok based on the same principal but doesn't replicate the main DFV features very well in my view.
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Angle of wrap and number of teeth engaged at the crank is pretty small.
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Hi Steamer, I agree it doesn't give much engagement but working back from the cam pulley size restriction it's the biggest I can get on the crank.
The bouland engine below is 1/3rd scale and looks like its using a 12.7mm single belt driving both cam shafts from a similar small crank pulley.
Jon
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Dave (Steamer)
The crankshaft pulley is the small one at the very bottom with nearly 180* of wrap.
Jon,
Instead of using two narrow belts to overcome the cylinder stagger, why not use one wider belt and overcome the cylinder stagger by increasing the length of the cam shafts on one side, by the amount of the cylinder stagger. That's what Mercedes Benz did on the W165 to bring their cam shaft drive all onto the same plane.
Mike
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Hi Mike,
I thought about that. Bouland must be doing it as he's running one belt only. it would mean a complete redesign of the front cover to bring everything level but that's doable. I just wanted to keep everything as true to the real thing as possible and came up with this layout.
Do we think it would work? If Bouland is using a 12.7 belt to drive four cams then would 6mm work on just two?
Jon
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Hi Steamer, I agree it doesn't give much engagement but working back from the cam pulley size restriction it's the biggest I can get on the crank.
The bouland engine below is 1/3rd scale and looks like its using a 12.7mm single belt driving both cam shafts from a similar small crank pulley.
Jon
Mike and Jon, What size is the crank shaft pulley?.....
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Hello Jon,
In principle two narrow belts should do the same work as one wider one. Have a look at different belt manufacturers, some offer better strength and some offer greater flexibility/
.
Mike
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My usual starting point for actual designs (when I am not winging it) is: https://sdp-si.com/D820/PDFS/Technical-Section.pdf
6 teeth seems to be minimum wrap. Belts that are wider than diameter of pulley give tracking issues. Short belts also give tracking issues. Roundinsh profiles have less cogging action and don't tend to ride up the pulley as much. But their profiles are generally proprietary although the sdp-si manual conveniently gives the related patent numbers for further educaation. They can apparently be approximated using ball nose end mills and cnc. :-)
One suggestion might be to gear drive from crank to the large central pulley, then single belt from there around al the cams. Outside idlers are preferred over ones riding on teeth.
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My usual starting point for actual designs (when I am not winging it) is: https://sdp-si.com/D820/PDFS/Technical-Section.pdf
6 teeth seems to be minimum wrap. Belts that are wider than diameter of pulley give tracking issues. Short belts also give tracking issues. Roundinsh profiles have less cogging action and don't tend to ride up the pulley as much. But their profiles are generally proprietary although the sdp-si manual conveniently gives the related patent numbers for further educaation. They can apparently be approximated using ball nose end mills and cnc. :-)
One suggestion might be to gear drive from crank to the large central pulley, then single belt from there around al the cams. Outside idlers are preferred over ones riding on teeth.
Yeah I was heading in that direction......
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Ferrari 308 method:
Single helical gear on crank driving 2 cam drive gears with pulleys. Good for repeated 7500 rpm from my experience :-)
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Or...even just a single reduction gear off the crank to a single timing belt pulley driving two belts, with a larger diameter so more tooth engagement....but if you have 6 teeth engaged at 180....you're probably fine....just looks small.
Dave
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Hi Steamer, I agree it doesn't give much engagement but working back from the cam pulley size restriction it's the biggest I can get on the crank.
The bouland engine below is 1/3rd scale and looks like its using a 12.7mm single belt driving both cam shafts from a similar small crank pulley.
Jon
Mike and Jon, What size is the crank shaft pulley?.....
Dave, it's 3/8" diameter and cam pulley 3/4" diameter
Jon
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My usual starting point for actual designs (when I am not winging it) is: https://sdp-si.com/D820/PDFS/Technical-Section.pdf
6 teeth seems to be minimum wrap. Belts that are wider than diameter of pulley give tracking issues. Short belts also give tracking issues. Roundinsh profiles have less cogging action and don't tend to ride up the pulley as much. But their profiles are generally proprietary although the sdp-si manual conveniently gives the related patent numbers for further educaation. They can apparently be approximated using ball nose end mills and cnc. :-)
One suggestion might be to gear drive from crank to the large central pulley, then single belt from there around al the cams. Outside idlers are preferred over ones riding on teeth.
Gerrit,
Some useful info, thanks. I think having two belts running next to each other may cause problems if they don't track perfectly and there's no room for a central flange to separate them.
A take off from an intermediate off the crank sounds like a plan.
Jon
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Hmm, problem.
I need to keep the top centre pulley running at half crank speed. It drives the auxiliary pullies for the water and oil pumps as well as the distributor.
Lucky old Mr Duckworth didn't have this problem before the invention of toothed belts.
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Hmm, problem.
I need to keep the top centre pulley running at half crank speed. It drives the auxiliary pullies for the water and oil pumps as well as the distributor.
Lucky old Mr Duckworth didn't have this problem before the invention of toothed belts.
You could gear drive off the crank to the intermediate pulley and drive everything else with belts from there....
That's what I was getting at ....
Dave
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Got it. I'll have a play with some layouts.
Thanks Dave :ThumbsUp:
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I think having two belts running next to each other may cause problems if they don't track perfectly and there's no room for a central flange to separate them.
Jon
Would you have enough room to fit two plain toothed pulleys ( i.e. without end flanges) onto the crankshaft with a thin 10 thou (0.25mm) washer between them to act as a combined flange, to stop the two belts rubbing and fighting each other?
Mike
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Mike, yes that would work or maybe just slice them to bits :Lol:
I cant do anything in the way of an intermediate arrangement off the crank and then another off to the cams as this inevitably creates a third step in the train.
I've ordered some standard pullies 9.55mm Diameter and 19.1mm diameter and will mock up the arrangement to see what sort of load it can take.
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Mike, yes that would work or maybe just slice them to bits :Lol:
Ummm!!! a Cosworth powered bacon slicer Interesting idea :facepalm:
Mike
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Hi all,
I haven't posted for a while. I hope everyone is keeping well.
I've been working on the moulds for the belt driven DFV and have been on a bit of a journey of realization that although something can be drawn to look like it will work, the reality can sometime be very different.
I drew up the belt driven version with some modifications ie cylinder stagger to allow for 6mm belts etc but thought it best to then replicate what would be the finished machined version from it. I then realised that there were numerous issues with clearances and wall thicknesses that had to be rectified.
The result has been countless toing and froing between mould and machined in order to achieve something that hopefully is a viable working model.
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Hello Jon,
That looks to be a very practical solution to the staggered cylinders and belts. :ThumbsUp: :ThumbsUp: :ThumbsUp:
I assume the crankshaft pulley has the two belts running side by side.
I am impressed with your idea of building a plastic mock-up to tease out all the tolerance and clearance issues before you commit to the castings. You cannot afford to find problems, once the die is cast, as they say.
Mike
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An interesting development. As I recall the Cosworth developments were first the FVA (four valve Anglia based on the Ford engine) then came the BDA (belt drive Anglia, heavily developed for rallying) and the DFV (double four valve Formula 1 engine). There was also a development of the Ford V6 with belt driven four valve heads.
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Hello Jon,
That looks to be a very practical solution to the staggered cylinders and belts. :ThumbsUp: :ThumbsUp: :ThumbsUp:
I assume the crankshaft pulley has the two belts running side by side.
I am impressed with your idea of building a plastic mock-up to tease out all the tolerance and clearance issues before you commit to the castings. You cannot afford to find problems, once the die is cast, as they say.
Mike
Mike,
the block moulds are printed in six different parts, hence the elastic bands holding it together, it's the only way to produce the waxes. I have splits the "machined" print in the same way in order to try and maintain accuracies (less support area etc)
because this produces a much better quality print of a complex shape, I'm also applying it to the "true" DFV model (geared etc) meaning that it should be easier for people to print themselves. Also there's less likelihood of scrapping a print because one area failed.
Maybe your cheap Chinese printer might still be able to produce a decent model?
Jon
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An interesting development. As I recall the Cosworth developments were first the FVA (four valve Anglia based on the Ford engine) then came the BDA (belt drive Anglia, heavily developed for rallying) and the DFV (double four valve Formula 1 engine). There was also a development of the Ford V6 with belt driven four valve heads.
Hi Roger,
Yes you are correct. Maybe this is the FVBDA and not DFV ? I'm sure Mr Duckworth would've preferred to work with belts rather then multiple gear trains?
jon
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Mike,
...............Also there's less likelihood of scrapping a print because one area failed.
Maybe your cheap Chinese printer might still be able to produce a decent model?
Jon
No chance, I gave up on the 'cheap as chips' Chinese printer and gave it to my grandson to play with.
Mike
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Hello Jon,
That looks to be a very practical solution to the staggered cylinders and belts. :ThumbsUp: :ThumbsUp: :ThumbsUp:
I assume the crankshaft pulley has the two belts running side by side.
I am impressed with your idea of building a plastic mock-up to tease out all the tolerance and clearance issues before you commit to the castings. You cannot afford to find problems, once the die is cast, as they say.
Mike
Hi Mike,
Yes, both belts run off the crankshaft
Jon
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Jon:
That printed tire master that you showed back in Post #45 was outstanding! What material did you use to print it, and what printer did you print it on?
Don
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Hi Don, thank for the comments. It's all PLA printed on a cheap Labists FDM printer with Simplify3D slicer.
Jon
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Jon:
What was the layer height? I've gone down to 0.1mm and I can still see the layers. I couldn't see any layers in that picture and I thought maybe you used a resin printer.
Don
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Hi Don,
I think I used 0.2mm layer height and then did a lot of post process filling and sanding. I also printed it in three sections, the first was half the tyre including a side wall but because this needed a load of support I did the other half of the tyre by printing just the outer diameter and then the side wall separately and then glued it all together. This is a master for a mould I'm making so they can be produced in rubber so only the outer detail was important.
BTW, the AVON lettering is also printed separately and the very small lettering I bought and again glued them both on.
Hope this helps
Jon
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Very impressive results - looking forward to see how you mould them!
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Very impressive results - looking forward to see how you mould them!
Agreed. What was used for glue on the PLA, and what as a filler?
--Tim
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Jon:
When you showed the inside of the tire I can see that you did indeed do a lot of post-processing - excellent work!
When you say you printed the AVON separately and glued it on, do you mean that printed the letters flat and then glued them on the curved tire, or did you print the letters on a section of the tire?
Like Tim, I'd like to know what you used for a glue. I've used Weldon 4 as a PLA solvent cement before and had fairly good luck. I used it on a red filament and for some reason it bleached the red out of the filament, the bond was excellent though. Apparently I didn't have the cap screwed on tight enough to the can, because when I wanted to use it several weeks/months later it had completely evaporated. I've read that Weldon 3 doesn't evaporate as fast as Weldon 4 so maybe that would be a better choice. Or maybe even Weldon 16, since it is thicker still and comes in a tube.
Don
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Hi Don,
I just use super glue. The AVON was printed flat with just a couple of 0.1mm layers and connectors to all the letters and other areas where they are free, ie the centre of the A etc. I then curved the whole set over a similar radius prior to gluing onto the tyre. The connectors were then cut off.
We have some really good aggressive Emery we use at work that makes the sanding really easy. I’ve used commercial body filler before for major filling and Humbrol fine filler for more detailed work.
Ive already moulded rubber spark plug bungs and CV boots for the DFV and FG400 so I’m hoping the tyre works as well, although I’m now told that they ran Goodyear’s in the 70’s
Jon
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Jon:
From the quality of your master I think your tires will be just fine. How thin of a tire cross-section are you planning on molding? Getting the mold for the tire interior out of the completed tire will be the big challenge. How many parts do you think the completed tire mold will be made of?
Don
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Hi Don,
I've taken a guess at the cross sections. The walls are squared off internally to try and ensure some strength when supporting the car and are 4mm at the thickest part. The diameter is only 2mm thick but I'll add some support in the way of a foam ring if it's not sufficient.
I've thought about various ways of making the internal mold so it can be extracted and come up with a 12 piece segmented 3D print that will hopefully work.
The finished tyre will be ultimately be from a two part mold with the split line around the corner step of the tyre.
Jon
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Love the sliding dovetails on the inner mould pieces. :popcorn: :popcorn: :popcorn:
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Jon:
Will the tire compound be soft enough with a 4mm wall thickness to give you a realistic tire contact patch?
Also are you planning on using anything to seal the gaps between the mold segments? When I molded the silicon boot for the hot block on my 3D printer I also used a 3D printed mold. I didn't seal the gaps between the mold sections and I got flash in every joint. (I allowed 0.25mm between parts, and there were 7 parts to that mold.) Any flash between your sliding segments might make it hard to remove the segment after the tire is cured.
Don
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Fill the gaps between the mold segments with a good dollop of petroleum jelly (Vaseline). If you use a paintbrush, you will get an even coating of the jelly on all surfaces and it will act as an excellent release agent
Mike :thinking:
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Some good advice Don, Mike, probably saved me a load of time and effort getting the thing out.
Don, I’ve molded the rubber I’m using before on the rubber boots of the DF400 gearbox CV joints and it seems fairly rigid for the section. I can always reprint the segments if needed.
Jon
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What kind of rubber are you using? Only types I've used is the two-part silicone.
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Hi Crueby,
Same, Polytek 50 PU casting rubber
Jon