By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Dec 6th

DIY Bed Gap

Is this a good idea or not?

All Topics | Latest Posts

Search for:  in Thread Title in  
not done it yet24/04/2019 17:43:23
3583 forum posts
15 photos
Posted by Clive Brown 1 on 24/04/2019 16:18:20:

....

Being a Saab, these discs were quirky in that they included a drum for the separate hand-brake shoes. The working surface of these drums corroded very badly, as they didn't ever do any real work,. I could skim them with the same set-up.

Clive

Not particularly quirky or only Saab. Peugeot rear brakes had drums for the handbrake. They changed, between 2002 and 2005, to hand brakes using the discs.

David Standing 124/04/2019 17:51:02
1280 forum posts
46 photos
Posted by not done it yet on 24/04/2019 17:43:23:
Posted by Clive Brown 1 on 24/04/2019 16:18:20:

....

Being a Saab, these discs were quirky in that they included a drum for the separate hand-brake shoes. The working surface of these drums corroded very badly, as they didn't ever do any real work,. I could skim them with the same set-up.

Clive

Not particularly quirky or only Saab. Peugeot rear brakes had drums for the handbrake. They changed, between 2002 and 2005, to hand brakes using the discs.

If I recall correctly, at one time under the Motor Vehicle Construction and Use Regulations in force at that time, from a safety point of view, handbrake mechanisms had to be mechanical, and not hydraulic, operated. The drum within a disc arrangement got round this requirement.

David George 124/04/2019 18:25:05
avatar
974 forum posts
314 photos

Hi Terry I worked on a 3 ft swing flat belt flat bed lathe and we needed to swing some plates with a 3ft 6 inch swing so we just got some 8 inch packing blocks under the head a bit more extreme than your disks but it solved a problem without major mod to lathe.

David

SillyOldDuffer24/04/2019 18:25:50
4864 forum posts
1021 photos

Well, it's Terry's lathe and he can do what he likes with it!

Bodge maybe, but it's an inexpensive modern machine unlikely to become a collectors item. It's just a tool.

Cutting off the section of prism Terry highlighted is unlikely to effect the rigidity of the bed much; I think on the 290 the rear V stops at the headstock anyway. The rear prism has no function at that point - the tailstock can't get anywhere near the proposed gap unless the saddle's been removed.

Jason mentioned the problem that would put me off most which is the difficulty of getting tools close to a large disc on these machines. On these machines the saddle design makes it awkward to approach an unusually large diameter object without overhanging the tool risking chatter and poor finish.

Why Terry's brake discs have such short lives only he can answer. Moving heavy loads in hilly terrain near salt water would do maximum damage. Friend of mine traced his problem to being a keen musician performing 2 or 3 times a week. With the band's heavy kit packed into his car his late night drive home included a long empty ring-road where he would hammer up to several roundabouts at 70mph (possibly faster, ahem) and then slam the brakes on just in case. His discs lasted a lot longer when he took to driving less enthusiastically!

Dave

Dave Halford24/04/2019 18:30:32
491 forum posts
4 photos
Posted by Clive Brown 1 on 24/04/2019 16:18:20:

I once wanted to skim the brake discs from a Saab 99. These wouldn't quite fit on my Boxford ME10 so I put spacers under the headstock, which turned it into a ME10.5. Job went quite well as I remember with a carbide tiped tool.

Being a Saab, these discs were quirky in that they included a drum for the separate hand-brake shoes. The working surface of these drums corroded very badly, as they didn't ever do any real work,. I could skim them with the same set-up.

Clive

latest Jeep Grandcherokee has the same system.

martin perman24/04/2019 18:58:26
avatar
1690 forum posts
70 photos

Surely the simplest method is to find a hire company or garage who has one of these **LINK** , no dismantling, quickly done.

Wheeler dealears use one in their programme, no connection with the company shown.

Martin P

Clive Brown 124/04/2019 19:09:20
287 forum posts
7 photos
Posted by Terry Kirkup on 24/04/2019 16:42:16: I agree that current steel discs ain't what they used to be quality wise. I've lost count of the ones I've changed just over the last five or more years, mainly on French motors but also Ford and Fiat. And I wait for Eurocarparts sales before buying new discs, they know my face well in the local branch now.

The Saab discs that I skimmed did have a minimum specified thickness for such work.

I'm not a car enthusiast but I thought that the reduced life of brake discs since the "olden days" stemmed at least in part fom the change from asbestos based maerials for the pads. This forced a change in the material spec. for the discs to a softer value.

The Novice Engineer24/04/2019 19:44:59
49 forum posts
22 photos

HI Myford did a special conversion of the ML7 that used raising blocks , catch up with the details here

http://www.lathes.co.uk/myfordcapstan/ Here

did consider doing this once, .... wokred out quicker and cheaper to buy new discs!

Steve

Edited By The Novice Engineer on 24/04/2019 19:46:02

Dennis Pataki24/04/2019 20:15:19
7 forum posts

To modify your lathe for more swing, you might consider fabricating an auxiliary spindle pedestal with it's centerline higher than that of your lathe's spindle.

This auxiliary spindle would be mounted on it's own bearings, it's pedestal be bolted to the lathe's bed, and be driven from the lathe's spindle via belt, gears, or roller chain.

You would have to set your cutting tool to a greater height to match the auxiliary spindle.

Accurate alignment would be necessary to avoid turning, boring, or facing tapers, although this might be an easy way to cut tapers if they are needed.

Alan Waddington 224/04/2019 22:09:44
448 forum posts
86 photos

Did a pair for a mate once as he was skint, foulest shittiest job ever, rust and crap everywhere, took forever to clean up afterwards, lathe, workshop and myself...........never again. face 17

Unless they off something exotic rare or classic, not worth the aggro, modern discs are dirt cheap and consumable

Personally wouldn’t consider butchering a lathe for the purpose.

Barrie Lever24/04/2019 23:07:16
323 forum posts
2 photos
Posted by David Standing 1 on 24/04/2019 17:51:02:
Posted by not done it yet on 24/04/2019 17:43:23:
Posted by Clive Brown 1 on 24/04/2019 16:18:20:

....

Being a Saab, these discs were quirky in that they included a drum for the separate hand-brake shoes. The working surface of these drums corroded very badly, as they didn't ever do any real work,. I could skim them with the same set-up.

Clive

Not particularly quirky or only Saab. Peugeot rear brakes had drums for the handbrake. They changed, between 2002 and 2005, to hand brakes using the discs.

If I recall correctly, at one time under the Motor Vehicle Construction and Use Regulations in force at that time, from a safety point of view, handbrake mechanisms had to be mechanical, and not hydraulic, operated. The drum within a disc arrangement got round this requirement.

David

I think those reg's actually refer to the handbrake as the emergency brake and if my memory is correct they have to show 20% of the braking capability of the main brake system on that axle.

I am sure that the emergency brake has to be independant of the main hydraulic system but quite a few cars use some nasty systems where a cam tensions the disk pads against the disk, no different really from an old drum brake setup.

The small hand brake drums within the hub of the disk are much the nicest system IMO, my SAAB is so reliable that I dont know what type of handbrake it has got, my old 944 defo had a mini drum for the hand brake.

Barrie

Hopper25/04/2019 05:43:08
avatar
3792 forum posts
79 photos
Posted by Terry Kirkup on 24/04/2019 13:09:45:

... re-facing the discs from the family's cars and my van which only seem to last a year these days.

Whaaaaat? Something ain't right there.

How many pairs of brake pads are you wearing out in that same one-year period? A disc should outlast many pairs of pads, or at least several.

Are you running cheapazz aftermarket brake pads that are gouging the discs up prematurely? You really need to pay for good quality pads, and discs. No way good quality ones will wear out in a year -- unless you are doing incredible high mileages which seems unlikely if you have multiple cars and a van.

You need to fix the cause of the problem, not go hacking up your perfectly good lathe to address the symptoms, over and over again every year.

Andrew Evans25/04/2019 08:24:12
272 forum posts
1 photos

Not sure what car you are running but a pair of quality discs for a Ford Focus are less than 30 quid and i would have thought would last 30k miles.

robjon4425/04/2019 08:57:14
112 forum posts

Hi all, add Astra GTE to list of cars with added drum for handbrake, would stick occasionally if left on for long periods ie on forecourt, I carried a hefty plastic mallet to deliver a clout to the middle of the wheel, only happened twice in 40,000 miles, otherwise car behaved like scalded cat.

Bob H

Howard Lewis25/04/2019 13:48:31
2460 forum posts
2 photos

using an Angle grinder on a good machine, sounds like sacrilige and butchery to me.Our last two cars, (Toyota Yaris ) needed new pads after 64K miles and still had the original discs when they left us.

If the discs need refacing every year, it sounds as if the vehicle must either must be standing in a vey saline atmosphere, or being driven and braked VERY hard.

Howard

Terry Kirkup25/04/2019 14:33:08
avatar
49 forum posts
36 photos

As I said, you all have me convinced it's a bad idea so thanks again for thatdiscs.jpg!

Here's the price of discs for my van, just for info. If I bought the best that would be £216 for the front only. Not as cheap as claimed elsewhere! But I don't buy the "best" and wait for cheap deals coming up. My offspring and their hubbies are all heavy-footed so-and-sos just like me, the wife's car is driven least and suffers most. There probably is something valid about the lack of asbestos in pads now but I think the steel is much inferior too. Most of the changes I am forced to make are due to steering wobble setting in, immediately cured with new discs, not heavy grooving or scoring.

I'm sorry to have dragged model engineering into a driving instructor's course! No further advice (on lathe butchery) required

Dave Halford25/04/2019 15:12:36
491 forum posts
4 photos

Terry,

Next time they wobble try driving at 70 on a quiet road and do a 'nearly' emergency stop, but don't actually stop. Then immediately do a second one, after a mile or so when the discs have cooled down try braking normally, the wobble should have gone.

The object is to get the brakes good and hot and re-distribute evenly the resin (glaze) that can form under the pads when people do a big stop at the top of motorway slip roads and leave their foot on the brakes to prevent rolling back. The patches of resin catch unevenly as those areas are 'grippyer ' than the rest of the disc and feel through the steering like the discs have warped (warped discs also make the brake pedal pulse a lot)

Of course you could get the same result by using a dial gauge on the disc to prove it's not warped, then sanding to glaze bust both sides of each disc, but that will take another hour per side.smiley

You should save enough cash to buy a new mill instead.

Terry Kirkup25/04/2019 15:36:24
avatar
49 forum posts
36 photos

Cheers Dave, appreciate the advice. I will certainly give this a go, shouldn't be too long

Edited By Terry Kirkup on 25/04/2019 15:36:53

Richard brown 125/04/2019 19:19:54
116 forum posts
32 photos

Isn't it funny that Terry has Golum as his picture but doesn't think his lathe is that precious!

Nigel McBurney 125/04/2019 19:50:30
avatar
623 forum posts
3 photos

in the past I have skimmed discs because I am mean,I have a blank of cast iron which has numerous tapped holes so that various dics will fit ,each time the blank is mounted in the chuck I skim the face of the cast blank ,absolute minimum,to ensure it is running dead true ,then make sure the mounting face of the disc has no burrs or dings and the car hub is clean and likewise free from burrs, clean off the disc,with wire brush and and use angle grinder to clean the o/dia where the pads do not touch. if after cleaning and grinding the disc brakes really do need skimming the bolt the disc to the iron blank this gets them really true,then skim to the desired finish,if the lathe is big and the disc small,there the possibilty of skimming both sides at one setting.I had one volvo that covered120000 miles without changing the discs,the o/dia was just cleaned with an angle grinder, one thing I did learn from a specialist volvo mechanic was always use genuine volve pads,I was using ferodo pads at the time and they squeaked and despite using all the well known remedies they still squeaked ,changed to genuine pads and the problem disapeared.My wife had a peugot 306 from new,ran it for 21 years and never replaced or skimmed the front discs ,again only the rusty outer o/dia was cleaned off occasionally. Our cars are always garaged which does help stop the corrosion.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Allendale Electronics
Ausee.com.au
Tee London LMES 6th Dec
Eccentric Engineering
Warco
Eccentric July 5 2018
emcomachinetools
cowells
ChesterUK
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest